Filed Pursuant to Rule 424(b)(3)
Registration Number 333-221942

MERGER PROPOSED—YOUR VOTE IS VERY IMPORTANT

Potlatch Corporation, referred to as Potlatch, Portland Merger LLC, a wholly-owned subsidiary of Potlatch, referred to as Merger Sub, and Deltic Timber Corporation, referred to as Deltic, have entered into an Agreement and Plan of Merger, dated as of October 22, 2017, referred to as the merger agreement. Pursuant to the terms of the merger agreement, Deltic will merge with and into Merger Sub, referred to as the merger, with Merger Sub continuing as the surviving entity in the merger.

If the merger is completed, Deltic stockholders will have the right to receive 1.80 shares of Potlatch common stock for each share of Deltic common stock, with cash paid in lieu of fractional shares. This exchange ratio is fixed and will not be adjusted to reflect stock price changes prior to the completion of the merger. Based on the closing price of shares of Potlatch common stock on the Nasdaq Global Select Market, on October 20, 2017, the last trading day before public announcement of the merger, the 1.80 exchange ratio represented approximately $95.40 in value for each share of Deltic common stock. Based on the closing price of shares of Potlatch common stock on the Nasdaq Global Select Market on January 17, 2018, the latest practicable date before the date of this joint proxy statement/prospectus, the 1.80 exchange ratio represented approximately $94.41 in value for each share of Deltic common stock. Potlatch stockholders will continue to own their existing Potlatch common stock. Shares of Potlatch common stock are currently traded under the symbol “PCH” on the Nasdaq Global Select Market, and shares of Deltic common stock are currently traded under the symbol “DEL” on the New York Stock Exchange. Following the completion of the merger, Potlatch will be known as PotlatchDeltic and its common stock will continue to trade under the symbol “PCH” on the Nasdaq Global Select Market. We urge you to obtain current market quotations of shares of Potlatch common stock and shares of Deltic common stock.

Based on the estimated number of shares of Potlatch common stock and shares of Deltic common stock that will be outstanding immediately prior to the completion of the merger, we estimate that current Potlatch stockholders will own approximately 65% of the combined company and former Deltic stockholders will own approximately 35% of the combined company.

Potlatch and Deltic will each hold special meetings of their respective stockholders in connection with the proposed merger.

At the special meeting of Potlatch stockholders, Potlatch stockholders will be asked to consider and vote on (1) a proposal to approve the issuance of shares of Potlatch common stock to Deltic stockholders in connection with the merger, referred to as the share issuance proposal, and (2) a proposal to adjourn the Potlatch special meeting, if necessary or appropriate, to solicit additional proxies if there are not sufficient votes to approve the issuance of shares of Potlatch common stock to Deltic stockholders in connection with the merger, referred to as the Potlatch adjournment proposal. The Potlatch board of directors unanimously recommends that the Potlatch stockholders vote “FOR” each of the share issuance proposal and the Potlatch adjournment proposal.

At the special meeting of Deltic stockholders, Deltic stockholders will be asked to consider and vote on (1) a proposal to approve the adoption of the merger agreement, referred to as the merger proposal, (2) a proposal to adjourn the Deltic special meeting, if necessary or appropriate, to solicit additional proxies if there are not sufficient votes to adopt the merger agreement, referred to as the Deltic adjournment proposal, and (3) a non-binding, advisory proposal to approve the compensation that may be paid or become payable to Deltic’s named executive officers in connection with the completion of the merger, referred to as the

compensation proposal. The Deltic board of directors unanimously recommends that the Deltic stockholders vote “FOR” each of the merger proposal, the Deltic adjournment proposal and the compensation proposal.

We cannot complete the merger unless Potlatch stockholders approve the share issuance proposal and Deltic stockholders approve the merger proposal. Your vote is very important, regardless of the number of shares you own. Whether or not you expect to attend your special meeting in person, please vote your shares as promptly as possible by (1) accessing the Internet website specified on your proxy card, (2) calling the toll-free number specified on your proxy card or (3) marking, signing, dating and returning all proxy cards that you receive in the postage-paid envelope provided, so that your shares may be represented and voted at the Potlatch or Deltic special meeting, as applicable.

The obligations of Potlatch and Deltic to complete the merger are subject to the satisfaction or waiver of several conditions set forth in the merger agreement. More information about Potlatch, Deltic and the merger is contained in this joint proxy statement/prospectus. Potlatch and Deltic encourage you to read this entire joint proxy statement/prospectus carefully before voting, including the section entitled “Risk Factors” beginning on page 28.

We look forward to the successful combination of Potlatch and Deltic.

Sincerely,

Michael J. Covey		John D. Enlow, Sr.
Chairman and Chief Executive Officer		President and Chief Executive Officer
Potlatch Corporation		Deltic Timber Corporation

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of the securities to be issued under this joint proxy statement/prospectus or determined that this joint proxy statement/prospectus is accurate or complete. Any representation to the contrary is a criminal offense.

This joint proxy statement/prospectus is dated January 18, 2018 and is first being mailed to the stockholders of Potlatch and stockholders of Deltic on or about January 19, 2018.

Potlatch Corporation

601 West First Avenue, Suite 1600

Spokane, Washington 99201

(509) 835-1500

NOTICE OF SPECIAL MEETING OF STOCKHOLDERS

To Be Held On February 20, 2018

Dear Stockholders of Potlatch Corporation:

We are pleased to invite you to attend the special meeting of stockholders of Potlatch Corporation, a Delaware corporation (referred to as “Potlatch”), which will be held at the Potlatch corporate offices located at 601 West First Avenue, Suite 1600, Spokane, Washington 99201, on February 20, 2018, at 9:00 a.m. local time, for the following purposes:

Potlatch will transact no other business at the special meeting except such business as may properly be brought before the special meeting or any adjournment or postponement of the special meeting. Please refer to the joint proxy statement/prospectus accompanying this notice for further information with respect to the business to be transacted at the special meeting.

The Potlatch board of directors has fixed the close of business on January 17, 2018 as the record date for determination of Potlatch stockholders entitled to receive notice of, and to vote at, the special meeting and any adjournments or postponements of the special meeting. Only stockholders of record of shares of Potlatch common stock as of the close of business on the record date are entitled to notice of, and to vote at, the special meeting and any adjournments or postponements of the special meeting. A list of stockholders of record entitled to vote at the special meeting will be available beginning 10 days prior to the special meeting, and continuing through the special meeting, at Potlatch’s executive offices and principal place of business at 601 West First Avenue, Suite 1600, Spokane Washington for inspection by stockholders during ordinary business hours for any purpose germane to the special meeting. The list will also be available at the special meeting for examination by any stockholders of record present at the special meeting.

Approval of the share issuance proposal and the Potlatch adjournment proposal requires that votes cast “FOR” exceed the votes cast “AGAINST” each proposal (with abstentions and broker non-votes not considered votes cast).

Your vote is very important. Whether or not you expect to attend in person, we urge you to vote your shares as promptly as possible by (1) accessing the Internet website specified on your proxy card, (2) calling the toll-free number specified on your proxy card or (3) marking, signing, dating and returning the enclosed proxy card in the postage-paid envelope provided, so that your shares may be represented and voted at the special meeting. If your shares are held in the name of a bank, broker or other holder of record, please follow the instructions on the voting instruction card furnished by the bank, broker or other holder of record.

Please note that if you hold shares in different accounts, it is important that you vote the shares represented by each account.

The joint proxy statement/prospectus accompanying this notice provides a detailed description of the merger and the merger agreement. We encourage you to read the accompanying joint proxy statement/prospectus, including any documents incorporated by reference and the annexes to the joint proxy statement/prospectus, carefully and in their entirety. If you have any questions concerning the merger or the joint proxy statement/prospectus, would like additional copies or need help voting your shares of Potlatch common stock, please contact Potlatch’s proxy solicitor:

Georgeson LLC

1290 Avenue of the Americas, 9th Floor

New York, New York 10104

(888) 565-5423 (toll-free)

Spokane, Washington

January 18, 2018

DELTIC TIMBER CORPORATION

210 East Elm Street

El Dorado, Arkansas 71730

(870) 881-9400

NOTICE OF SPECIAL MEETING OF STOCKHOLDERS

To Be Held On February 20, 2018

Dear Stockholders of Deltic Timber Corporation:

We are pleased to invite you to attend the special meeting of stockholders of Deltic Timber Corporation, a Delaware corporation (referred to as “Deltic”), which will be held at 210 East Elm Street, El Dorado, Arkansas 71730, on February 20, 2018, at 11:00 a.m. local time, for the following purposes:

Deltic will transact no other business at the special meeting except such business as may properly be brought before the special meeting or any adjournment or postponement of the special meeting. Please refer to the joint proxy statement/prospectus accompanying this notice for further information with respect to the business to be transacted at the special meeting.

The Deltic board of directors has fixed the close of business on January 17, 2018 as the record date for determination of Deltic stockholders entitled to receive notice of, and to vote at, the special meeting and any adjournments or postponements of the special meeting. Only stockholders of record of shares of Deltic common stock as of the close of business on the record date are entitled to notice of, and to vote at, the special meeting and any adjournments or postponements of the special meeting. A list of stockholders of record entitled to vote at the special meeting will be available for 10 days prior to the special meeting at Deltic’s executive offices and principal place of business at 210 East Elm Street, El Dorado, Arkansas 71730 for inspection by stockholders during ordinary business hours for any purpose germane to the special meeting. The list will also be available at the special meeting for examination by any stockholder of record present at the special meeting.

Approval of the merger proposal requires the affirmative vote of the holders of a majority of the issued and outstanding shares of Deltic common stock entitled to vote at the special meeting. Approval of the Deltic adjournment proposal and the compensation proposal each requires that votes cast “FOR” exceed the votes cast “AGAINST” each proposal (with abstentions and broker non-votes not considered votes cast).

Your vote is very important. Whether or not you expect to attend in person, we urge you to vote your shares as promptly as possible by (1) accessing the Internet website specified on your proxy card, (2) calling the toll-free number specified on your proxy card or (3) marking, signing, dating and returning the enclosed proxy card in the postage-paid envelope provided, so that your shares may be represented and voted at the special meeting. If your shares are held in the name of a bank, broker or other holder of record, please follow the instructions on the voting instruction card furnished by the bank, broker or other holder of record.

Please note that if you hold shares in different accounts, it is important that you vote the shares represented by each account.

The joint proxy statement/prospectus accompanying this notice provides a detailed description of the merger and the merger agreement. We encourage you to read the accompanying joint proxy statement/prospectus, including any documents incorporated by reference, and the annexes to the joint proxy statement/prospectus carefully and in their entirety. If you have any questions concerning the merger or the joint proxy statement/prospectus, would like additional copies or need help voting your shares of Deltic common stock, please contact Deltic’s proxy solicitor:

Georgeson LLC

1290 Avenue of the Americas, 9th Floor

New York, New York 10104

(800) 279-6913 (toll-free)

By Order of the Board of Directors,

Jim F. Andrews, Jr.

Vice President, General Counsel & Secretary

El Dorado, Arkansas

January 18, 2018

ADDITIONAL INFORMATION

This joint proxy statement/prospectus incorporates important business and financial information about Potlatch and Deltic from other documents that are not included in, or delivered with, this joint proxy statement/prospectus. This information is available to you without charge upon your request. You can obtain the documents incorporated by reference into this joint proxy statement/prospectus by requesting them in writing or by telephone from the appropriate company at the following addresses and telephone numbers:

In order for you to receive timely delivery of the documents in advance of the Potlatch special meeting or the Deltic special meeting, as applicable, you must request the information no later than five business days prior to the date of the special meetings (i.e., by February 12, 2018).

For more information, see the section entitled “Where You Can Find More Information” beginning on page 188.

ABOUT THIS JOINT PROXY STATEMENT/PROSPECTUS

This joint proxy statement/prospectus, which forms part of a registration statement on Form S-4 filed with the U.S. Securities and Exchange Commission (referred to as the “SEC”) by Potlatch (File No. 333-221942), constitutes a prospectus of Potlatch under Section 5 of the Securities Act of 1933, as amended (referred to as the “Securities Act”), with respect to the shares of Potlatch common stock to be issued to Deltic stockholders pursuant to the merger agreement. This joint proxy statement/prospectus also constitutes a joint proxy statement under Section 14(a) of the Securities Exchange Act of 1934, as amended (referred to as the “Exchange Act”). It also constitutes a notice of meeting with respect to the special meeting of Potlatch stockholders and a notice of meeting with respect to the special meeting of Deltic stockholders.

Potlatch and Deltic have not authorized anyone to provide you with any information other than the information that is contained in, or incorporated by reference into, this joint proxy statement/prospectus. Potlatch and Deltic take no responsibility for, and can provide no assurances as to the reliability of, any other information that others may give you. This joint proxy statement/prospectus is dated January 18, 2018. You should not assume that the information contained in this joint proxy statement/prospectus is accurate as of any date other than that date. Further, you should not assume that the information incorporated by reference into this joint proxy statement/prospectus is accurate as of any date other than the date of the incorporated document. Neither the mailing of this joint proxy statement/prospectus to Potlatch stockholders or Deltic stockholders, nor the issuance by Potlatch of shares of common stock in connection with the merger, will create any implication to the contrary.

This joint proxy statement/prospectus does not constitute an offer to sell or the solicitation of an offer to buy any securities, or the solicitation of a proxy, in any jurisdiction to or from any person to whom it is unlawful to make any such offer or solicitation in such jurisdiction. Information contained in this joint proxy statement/prospectus regarding Potlatch has been provided by Potlatch, and information contained in this joint proxy statement/prospectus regarding Deltic has been provided by Deltic.

Unless otherwise indicated or as the context otherwise requires, all references in this joint proxy statement/prospectus to:

TABLE OF CONTENTS

The following are some questions that you, as a stockholder of Potlatch or Deltic, may have regarding the merger and the other matters being considered at the special meetings and the answers to those questions. Potlatch and Deltic encourage you to read carefully the remainder of this joint proxy statement/prospectus because the information in this section does not provide all the information that might be important to you with respect to the merger and the other matters being considered at the special meetings. Additional important information is also contained in the annexes to this joint proxy statement/prospectus and the documents incorporated by reference into this joint proxy statement/prospectus. See the section entitled “Where You Can Find More Information” beginning on page 188 for the location of information incorporated by reference in this joint proxy statement/prospectus.

This joint proxy statement/prospectus serves as the proxy statement through which Potlatch and Deltic will solicit proxies to obtain the necessary stockholder approval in connection with the proposed merger. It also serves as the prospectus by which Potlatch will issue shares of Potlatch common stock as the merger consideration.

In order to complete the merger, among other things, Potlatch stockholders must vote to approve the issuance of Potlatch common stock to Deltic stockholders in connection with the merger and Deltic stockholders must vote to adopt the merger agreement.

Potlatch and Deltic will hold separate special meetings to obtain these approvals. This joint proxy statement/prospectus contains important information about the merger and the Potlatch special meeting and Deltic special meeting, and you should read this joint proxy statement/prospectus carefully and in its entirety. The enclosed voting materials allow you to vote your shares without attending your respective special meeting.

Your vote is very important. We encourage you to vote as soon as possible.

If the merger is completed, Potlatch stockholders will not receive any merger consideration and will continue to hold their shares of Potlatch common stock.

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The Deltic special meeting will be held at 11:00 a.m. local time on February 20, 2018, at Deltic corporate headquarters, 210 East Elm Street, El Dorado, Arkansas 71730, unless adjourned or postponed to a later date or time.

Potlatch will transact no other business at its special meeting except such business as may properly be brought before the Potlatch special meeting or any adjournment or postponement thereof.

At the special meeting of Deltic stockholders, Deltic stockholders will be asked to consider and vote on:

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Deltic will transact no other business at its special meeting except such business as may properly be brought before the Deltic special meeting or any adjournment or postponement thereof.

If you hold Potlatch shares in the name of a bank, broker or other holder of record, please follow the instructions on the voting instruction card furnished by the bank, broker or other holder of record to ensure that your shares are represented at the Potlatch special meeting.

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If you hold shares of Deltic common stock in the name of a bank, broker or other holder of record, please follow the instructions on the voting instruction card furnished by the bank, broker or other holder of record to ensure that your shares are represented at the Deltic special meeting.

Deltic. Approval of the merger proposal requires the affirmative vote of the holders of a majority of the issued and outstanding shares of Deltic common stock entitled to vote at the Deltic special meeting. Approval of the Deltic adjournment proposal and the compensation proposal each requires that votes cast “FOR” exceed the votes cast “AGAINST” each proposal (with abstentions and broker non-votes not considered votes cast).

Deltic. You are entitled to one vote for each share of Deltic common stock that you owned as of the close of business on January 17, 2018, the record date for the Deltic special meeting. As of the close of business on the record date for the Deltic special meeting, there were approximately 12,194,816 shares of Deltic common stock outstanding and entitled to vote at the Deltic special meeting.

Deltic. If you fail to vote, fail to instruct your bank, broker or other holder of record to vote, or vote to abstain, it will have the same effect as a vote against the merger proposal. If you fail to vote, fail to instruct your bank, broker or other holder of record to vote, or mark your proxy or voting instructions to abstain, it will have no effect on the Deltic adjournment proposal or the compensation proposal, assuming that a quorum is present.

Deltic. Stockholders who hold at least a majority of the issued and outstanding shares of Deltic common stock as of the close of business on the record date and who are entitled to vote must be present or

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represented by proxy in order to constitute a quorum for the transaction of business at the Deltic special meeting. Shares of Deltic common stock represented at the Deltic special meeting but not voted, including shares for which a stockholder directs an “abstention” from voting, will be counted as present for purposes of establishing a quorum. Broker non-votes (shares held by banks, brokers or other holders of record that are present, in person or by proxy, at the Deltic special meeting but with respect to which the bank, broker or other holder of record is not instructed by the beneficial owner of such shares how to vote on a particular proposal and the bank, broker or other holder of record does not have discretionary voting power on such proposal) will be counted as present for purposes of determining the presence of a quorum.

If you are a Potlatch stockholder and you do not provide your bank, broker or other holder of record with instructions:

If you are a Deltic stockholder and you do not provide your bank, broker or other holder of record with instructions:

Please note that you may not vote shares held in street name by returning a proxy card directly to Potlatch or Deltic or by voting in person at your special meeting unless you provide a “legal proxy,” which you must obtain from your bank, broker or other holder of record.

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If you choose either of the first two methods, you must submit your notice of revocation or your new proxy to the Corporate Secretary of Potlatch or Corporate Secretary of Deltic, as appropriate, no later than the beginning of the applicable special meeting. If your shares are held in street name by your bank, broker or other holder of record, you should contact your bank, broker or other holder of record to change your vote or revoke your proxy.

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In addition, as a result of the merger, Potlatch will succeed to all of Deltic’s “earnings and profits” for U.S. federal income tax purposes, and in order for Potlatch to maintain its REIT status following the merger, it must distribute all of such earnings and profits prior to the end of the taxable year in which the merger occurs. Accordingly, following the merger, Potlatch will make one or more special distributions, which distributions are expected in substantial part to be paid in cash or Potlatch stock at each stockholder’s

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election, with a limit on the aggregate amount of cash that will be available for such distribution (which limit may be as low as 20% under current guidance by the Internal Revenue Service (referred to as “IRS”)) (the foregoing dividends collectively, the “special distribution”). The special distribution will generally be taxable to Potlatch stockholders, including Deltic stockholders that become Potlatch stockholders in the merger, as ordinary income (and, to the extent attributable to Deltic’s “earnings and profits,” generally as “qualified dividend income” in the case of U.S. stockholders that are individuals, estates, or trusts), including in respect of the portion of the special distribution paid in Potlatch stock. Because the Potlatch stock received by a stockholder in the special distribution will be treated as a taxable distribution, the special distribution may give rise to a tax liability in excess of the amount of cash received by the stockholder subject to the discussion at “U.S. Federal Income Taxation of Potlatch and its Stockholders—Taxation of Stockholders—Distributions” beginning on page 113.

The particular consequences of the merger to each common stockholder depend on such holder’s particular facts and circumstances. Stockholders are urged to consult their tax advisors to understand fully the consequences to them of the merger in their specific circumstances. A more detailed discussion of the U.S. federal income tax considerations relevant to the merger can be found in the section entitled ‘‘U.S. Federal Income Tax Consequences of the Merger’’ beginning on page 100 of this joint proxy statement/prospectus.

Under the merger agreement, Potlatch and Deltic are required to coordinate with each other to designate the same record and payment dates for any quarterly dividends or distributions declared in accordance with the merger agreement in any calendar quarter in which the closing of the merger might reasonably be expected to occur so that (1) no holder of shares of Potlatch common stock or shares of Deltic common stock will receive two dividends, or fail to receive one dividend, for any single calendar quarter and (2) the quarterly payments of dividends to holders of shares of Potlatch common stock (and any necessary adjustments to Deltic’s schedule for quarterly dividends) will be made substantially in accordance with Potlatch’s historical quarterly dividend payment schedule.

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If you are a holder of record, in order for your shares to be represented at your special meeting:

If you hold your shares in street name, in order for your shares to be represented at your special meeting, you should instruct your bank, broker or other holder of record as to how to vote your shares, following the directions from your bank, broker or other holder of record provided to you.

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This joint proxy statement/prospectus and the documents incorporated by reference into this joint proxy statement/prospectus contain statements that are forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, including with respect to future results and performance, the expected benefits of the merger such as efficiencies, cost savings and growth potential and the expected timing of the merger. Factors listed below, as well as other factors, may cause actual results to differ significantly from these forward-looking statements. There is no guarantee that any of these events anticipated by these forward-looking statements will occur. If any of these events occur, there is no guarantee what effect they will have on operations or financial condition.

Forward-looking statements can be identified by the fact that they do not relate strictly to historical or current facts. They often use words such as “expects,” may,” “will,” “believes,” “should,” “approximately,” “anticipates,” “estimates,” “projects,” intends,” plans,” targets” or “approximately.” In addition, these words may use the positive or negative or other variations of those and similar words.

Major risks, uncertainties and assumptions that affect Potlatch’s and Deltic’s businesses and may cause actual results to differ materially from those expressed or implied in these forward-looking statements include those set forth in Potlatch’s and Deltic’s filings with the SEC, including their respective Annual Reports on Form 10-K for the fiscal years ended December 31, 2016, those set forth in the section entitled “Risk Factors” beginning on page 28, as well as, among others, risks, uncertainties and assumptions relating to:

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Potlatch and Deltic undertake no obligation to publicly update any forward-looking statement, whether as a result of new information, future events or otherwise. In the event that Potlatch or Deltic does update any forward-looking statement, no inference should be made that Potlatch or Deltic will make additional updates with respect to that statement, related matters or any other forward-looking statements.

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In addition to the other information included and incorporated by reference into this joint proxy statement/prospectus, including the matters addressed in the section entitled “Cautionary Statement Regarding Forward-Looking Statements” beginning on page 26, you should carefully consider the following risks before deciding whether to vote for the merger proposal, in the case of Deltic stockholders, or for the share issuance proposal, in the case of Potlatch stockholders. In addition, you should read and consider the risks associated with each of the businesses of Potlatch and Deltic because these risks will also affect the combined company. Descriptions of some of these risks can be found in Potlatch’s and Deltic’s respective Annual Reports on Form 10-K for the fiscal year ended December 31, 2016, as, in each case, updated by any subsequent Quarterly Reports on Form 10-Q and Current Reports on Form 8-K, all of which are filed with the SEC and incorporated by reference into this joint proxy statement/prospectus. You should also read and consider the other information in this joint proxy statement/prospectus and the other documents incorporated by reference into this joint proxy statement/prospectus. See the section entitled “Where You Can Find More Information” beginning on page  188.

Risk Factors Relating to the Merger

The exchange ratio is fixed and will not be adjusted in the event of any change in either Potlatch’s or Deltic’s stock price.

Under the terms of the merger agreement, at the effective time of the merger, each outstanding share of Deltic common stock (other than shares of Deltic common stock owned by Deltic as treasury stock, which will be canceled) will be converted into the right to receive 1.80 shares of Potlatch common stock. This exchange ratio of 1.80 was fixed in the merger agreement and will not be adjusted for changes in the market price of either shares of Potlatch common stock or shares of Deltic common stock. Changes in the price of shares of Potlatch common stock prior to the merger will affect the market value that Deltic stockholders will receive upon completion of the merger.

The price of shares of Potlatch common stock at the closing of the merger may vary from its price on the date the merger agreement was executed, on the date of this joint proxy statement/prospectus and on the date of the special meetings of Potlatch and Deltic. As a result, the market value represented by the exchange ratio will also vary. For example, based on the range of closing prices of shares of Potlatch common stock during the period from October 20, 2017, the last trading day before public announcement of the merger, through January 17, 2018, the latest practicable date before the date of this joint proxy statement/prospectus, the exchange ratio represented a market value ranging from a low of $87.75 to a high of $96.93 for each share of Deltic common stock. Accordingly, at the time of the Deltic special meeting, Deltic stockholders will not know or be able to determine the market value of the consideration they will receive upon completion of the merger.

Stock price changes may result from a variety of factors (many of which are beyond our control), including, among others, changes in our respective businesses, operations and prospects; changes in market assessments of the business, operations and prospects of either company; investor behavior and strategies; interest rates, general market and economic conditions and other factors generally affecting the price of shares of Potlatch’s common stock and shares of Deltic’s common stock; and federal, state and local legislation, governmental regulation, tariffs, quotas and trade agreements, and legal developments in the businesses in which Potlatch and Deltic operate.

Potlatch’s stock price may be negatively impacted by risks and conditions that apply to Potlatch, which are different from the risks and conditions applicable to Deltic.

Upon completion of the merger, holders of Deltic common stock will become holders of Potlatch common stock. The businesses of Potlatch differ from those of Deltic in important respects and, accordingly, the results of operations of Potlatch after the merger, as well as the market price of shares of Potlatch common stock, may be

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affected by factors different from those currently affecting or that have historically affected the independent results of operations of Deltic. Please see Potlatch’s Annual Report on Form 10-K for the fiscal year ended December 31, 2016, as updated by any subsequent Quarterly Reports on Form 10-Q, all of which are incorporated by reference in this joint proxy statement/prospectus (see the section entitled “Where You Can Find More Information” beginning on page 188 for the location of information incorporated by reference in this joint proxy statement/prospectus), and the section entitled “Cautionary Statements Regarding Forward-Looking Statements” beginning on page 28 for a summary of some of the key factors that might affect Potlatch and the prices at which shares of Potlatch common stock may trade from time to time.

Failure to complete the merger could negatively impact the stock prices and the future business and financial results of Potlatch and Deltic.

If the merger is not completed, the ongoing businesses of Potlatch or Deltic may be adversely affected and Potlatch and Deltic will be subject to several risks without realizing any of the benefits of having the merger completed, including the following:

In addition, if the merger is not completed, Potlatch or Deltic may be required, under certain circumstances, to pay a termination fee of $66 million and $33 million, respectively, to the other party.

Any delay in completing the merger, which is subject to a number of conditions, some of which are outside of the parties’ control, may reduce or eliminate the expected benefits from the transaction.

In addition to the required stockholder and stockholder approvals, the merger is subject to a number of other conditions beyond Potlatch’s and Deltic’s control that may prevent, delay or otherwise materially adversely affect its completion. Potlatch and Deltic cannot predict whether and when these other conditions will be satisfied. Furthermore, the requirements for obtaining the required approvals could delay the completion of the merger for a significant period of time or prevent it from occurring. Any delay in completing the merger could cause the combined company not to realize some or all of the synergies and other benefits that it expects to achieve if the merger is successfully completed within its expected time frame. The merger agreement contains certain restrictions on the conduct of the parties’ business. If the merger is delayed, these restrictions could adversely affect Potlatch’s or Deltic’s ability to execute business strategies or pursue attractive business opportunities. In addition, a delay could cause management of Potlatch or Deltic, as applicable, to focus on completion of the merger instead of on other opportunities that could be beneficial to Potlatch or Deltic. See the section entitled “The Issuance of Potlatch Common Stock and the Adoption of the Merger Agreement—The Merger Agreement—Conditions to Completion of the Merger” beginning on page 142.

In addition, if the merger is not completed by July 22, 2018, either Potlatch or Deltic may choose to terminate the merger agreement, subject to certain exceptions. Potlatch or Deltic may also choose to terminate the merger agreement in certain other circumstances, and the parties can mutually decide to terminate the merger agreement at any time prior to the completion of the merger, before or after the stockholder approvals have been

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obtained. See the sections entitled “The Merger Agreement—Termination of the Merger Agreement” beginning on page 143 and “—Expenses and Termination Fees” beginning on page 145.

The merger agreement contains provisions that could discourage a potential competing acquiror of either Potlatch or Deltic or could result in any competing proposal being at a lower price than it might otherwise be.

The merger agreement contains “no shop” provisions that, subject to limited exceptions, restrict Potlatch’s and Deltic’s ability to solicit, initiate, knowingly encourage or facilitate competing third-party proposals to acquire all or a significant part of Potlatch or Deltic. Further, even if the Potlatch board or Deltic board withdraws (or modifies in any manner adverse to the other party) or proposes publicly to withdraw (or modify in any manner adverse to the other party) its recommendation of the share issuance proposal or the merger proposal, as applicable, they will still be required to submit the matter to a vote of their respective stockholders at their respective special meetings unless the merger agreement is terminated in accordance with its terms. In addition, the other party generally has an opportunity to offer to modify the terms of the merger and the merger agreement in response to any takeover proposals that may be made before such board of directors may withdraw or modify its recommendation. In some circumstances, upon termination of the merger agreement, one of the parties may be required to pay a termination fee to the other party. For additional information, see the sections entitled “The Issuance of Potlatch Common Stock and the Adoption of the Merger Agreement—The Merger Agreement—No Solicitation of Alternative Proposals” beginning on page 136, “—Changes in Board Recommendations” beginning on page 137, “—Termination of the Merger Agreement” beginning on page 143 and “—Expenses and Termination Fees” beginning on page 145.

These provisions could discourage a potential competing acquiror that might have an interest in acquiring all or a significant part of Potlatch or Deltic from considering or proposing an acquisition, even if it were prepared to pay consideration with a higher per share cash or market value than that market value proposed to be received or realized in the merger, or might result in a potential competing acquiror proposing to pay a lower price than it might otherwise have proposed to pay because of the added expense of the termination fee that may become payable in certain circumstances.

The merger will involve substantial costs.

Potlatch and Deltic have incurred and expect to continue to incur substantial costs and expenses relating directly to the merger and the Potlatch share issuance, including fees and expenses payable to financial advisors, other professional fees and expenses, insurance premium costs, HSR filing fees, SEC filing fees, printing and mailing costs and other transaction-related costs, fees and expenses. Potlatch also will incur transaction fees and costs related to formulating and implementing integration plans, including facilities and systems consolidation costs, employment-related costs and costs related to the special distribution. Potlatch continues to assess the magnitude of these costs, and additional unanticipated costs may be incurred in the merger and the integration of the two companies’ businesses.

Uncertainty due to the pendency of the merger could adversely affect the business and operations of Potlatch or Deltic.

In connection with the pendency of the merger, some customers, suppliers or other entities with whom Potlatch or Deltic have a business relationship may delay or defer decisions, which could negatively impact revenues, earnings and cash flows of Potlatch or Deltic, as well as the market price of shares of Potlatch common stock or shares of Deltic common stock, regardless of whether the merger is completed. In addition, customers or suppliers may cease doing business with Potlatch, Deltic or the combined company in anticipation of or following the merger or may change the terms and conditions upon which they are willing to continue to do business. In addition, current or prospective competitors of Potlatch, Deltic or the combined company may seek to take advantage of potential uncertainty or disruption resulting from the merger to interfere with relationships with customers, suppliers or employees.

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Until the completion of the merger or the termination of the merger agreement in accordance with its terms, in consideration of the agreements made by the parties in the merger agreement, Potlatch and Deltic are each prohibited from entering into certain transactions and taking certain actions that might otherwise be beneficial to Potlatch or Deltic and their respective stockholders and stockholders.

Until the merger is completed, the merger agreement restricts Potlatch and Deltic from taking specified actions without the consent of the other party, and requires each of Potlatch and Deltic to operate in the ordinary course in all material respects. These restrictions may prevent Potlatch or Deltic from making appropriate changes to their respective businesses or pursuing attractive business opportunities that may arise prior to the completion of the merger. See the section entitled “The Issuance of Potlatch Common Stock and the Adoption of the Merger Agreement—The Merger Agreement—Conduct of Business” beginning on page 130.

The fairness opinions obtained by the boards of Potlatch and Deltic from their respective financial advisors will not reflect changes in circumstances between signing the merger agreement and the completion of the merger.

Neither the Potlatch board nor the Deltic board has obtained an updated fairness opinion as of the date of this joint proxy statement/prospectus from BofA Merrill Lynch, Potlatch’s financial advisor, or Goldman Sachs, Deltic’s financial advisor.

Changes in the operations and prospects of Potlatch or Deltic, general market and economic conditions and other factors that may be beyond the control of Potlatch or Deltic, and on which the fairness opinions were based, may alter the value of Potlatch or Deltic or the price of shares of Potlatch common stock or shares of Deltic common stock by the time the merger is completed. In particular, the pro forma financial information and forecasts provided by Potlatch and Deltic to their financial advisors at the time of such opinions did not reflect the impact of the H.R. 1, Tax Cuts and Jobs Act, enacted on December 22, 2017 (the “Tax Act”), which, among other things, decreased the U.S. corporate tax rate from 35% to 21%, before state and local income taxes. Based upon the information available as of the date of this joint proxy statement/prospectus, Potlatch and Deltic have performed analyses of the expected impact of the Tax Act and the change is expected to decrease the taxes paid by both Deltic and Potlatch for 2018 and future years. The opinions do not speak as of the time the merger will be completed or as of any date other than the dates of such opinions. The opinions are included as Annexes B and C to this joint proxy statement/prospectus. For a description of the opinion that the Potlatch board received from its financial advisor, see the section entitled “The Issuance of Potlatch Common Stock and the Adoption of the Merger Agreement—Opinion of Potlatch’s Financial Advisor” beginning on page 70. For a description of the opinion that the Deltic board received from its financial advisor, see the section entitled “The Issuance of Potlatch Common Stock and the Adoption of the Merger Agreement—Opinion of Deltic’s Financial Advisor” beginning on page 81. For a description of the factors considered by the Potlatch board in determining to approve the merger agreement and the merger, see the section entitled “The Issuance of Potlatch Common Stock and the Adoption of the Merger Agreement—Potlatch’s Reasons for the Merger; Recommendation of the Potlatch Board” beginning on page 62. For a description of the factors considered by Deltic’s board in determining to approve the merger agreement and the merger, see the section entitled “The Issuance of Potlatch Common Stock and the Adoption of the Merger Agreement—Deltic’s Reasons for the Merger; Recommendation of the Deltic Board” beginning on page 65.

Potlatch’s executive officers and directors and Deltic’s executive officers and directors have interests in the merger that may be different from, or in addition to, the interests of Potlatch’s stockholders and Deltic’s stockholders generally.

Executive officers of Potlatch and Deltic negotiated the terms of the merger agreement. The Potlatch board approved and adopted the merger agreement and approved the issuance of shares of Potlatch common stock to Deltic stockholders in connection with the merger and determined that the merger agreement and the transactions contemplated thereby, including the merger and the issuance of shares of Potlatch common stock to Deltic

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stockholders in connection with the merger, are in the best interests of Potlatch and its stockholders. The Deltic board unanimously determined that the merger agreement and the transactions contemplated by the merger agreement were advisable and in the best interests of Deltic and its stockholders and approved the merger agreement and the transactions contemplated by the merger agreement, including the merger. In considering these facts and the other information contained in this joint proxy statement/prospectus, you should be aware that Potlatch’s executive officers and directors and Deltic’s executive officers and directors may have financial interests in the merger that may be different from, or in addition to, the interests of Potlatch’s stockholders or Deltic’s stockholders. See the sections entitled “The Issuance of Potlatch Common Stock and the Adoption of the Merger Agreement—Financial Interests of Potlatch Directors and Officers in the Merger” on page 92 and “—Financial Interests of Deltic Directors and Officers in the Merger” on page 92.

The combined company may incur adverse tax consequences if Potlatch has failed or fails to qualify as a REIT for U.S. federal income tax purposes or as a result of Deltic’s status as a non-REIT “C corporation” for U.S. federal income tax purposes.

Potlatch has operated in a manner that it believes has allowed it to qualify as a REIT for U.S. federal income tax purposes under the Code and intends to continue to do so through and following the merger. Qualification as a REIT involves the application of highly technical and complex Code provisions for which there are only limited judicial and administrative interpretations. The determination of various factual matters and circumstances not entirely within the control of Potlatch may affect its ability to qualify as a REIT. In order to qualify as a REIT, Potlatch must satisfy a number of requirements, particularly relating to the nature of its assets and its income. A REIT must also make distributions to stockholders aggregating annually at least 90% of its net taxable income, excluding any capital gains.

If Potlatch has failed or fails to qualify as a REIT for U.S. federal income tax purposes and the merger is completed, the combined company may have significant tax liabilities.

If Potlatch loses its REIT status, or is determined to have lost its REIT status in a prior year, Potlatch will face serious tax consequences that could substantially reduce its cash available for distribution to its stockholders because:

Even if Potlatch retains its REIT status, because Deltic is not a REIT for U.S. federal income tax purposes, Potlatch and its stockholders (including Deltic stockholders that become Potlatch stockholders in the merger) will face the following adverse tax consequences:

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As a result of these factors, Potlatch’s failure (before or after the merger) to qualify as a REIT or Deltic’s status as a non-REIT “C corporation” could reduce Potlatch’s cash available for distribution to stockholders or impair its ability after the merger to expand its business and raise capital, could materially adversely affect the value of shares of Potlatch’s common stock, and could have other adverse effects for Potlatch and its stockholders.

Lawsuits have been filed, and other similar lawsuits may be filed against Deltic, the Deltic board and Potlatch, challenging the merger. An adverse ruling in any such lawsuit may prevent the merger from being completed.

Following announcement of the merger, two putative class action complaints, which we collectively refer to as the “complaints” in this joint proxy statement/prospectus, were filed by purported Deltic stockholders on behalf of a putative class of Deltic stockholders. The complaints, Amonte v. Deltic Timber Corp., et al., No. 1:17-cv-01812-UNA and Assad v. Deltic Timber Corp., et al., No. 1:18-cv-01005-SOH were filed in the United States District Court for the District of Delaware on December 18, 2017 and in the United States District Court for the Western District of Arkansas on January 9, 2018, respectively.

The complaints name as defendants different combinations of Deltic, members of the Deltic board, Potlatch and Merger Sub. The complaints generally assert that this joint proxy statement/prospectus contains disclosures that are either misleading or incomplete in violation of the Exchange Act and applicable SEC rules and regulations. The complaints seek different remedies, including, among other things, (a) injunctive relief enjoining the stockholder vote on the merger and consummation of the merger, (b) an award of the plaintiffs’ attorneys’ fees and costs in bringing the action and (c) such other and further relief as the court may deem just and proper.

The defendants believe that the claims asserted against them in the complaints are without merit and intend to defend the litigation vigorously. Additional lawsuits arising out of or relating to the merger agreement or the merger may be filed in the future.

See the section entitled “Litigation Related to the Merger” on page 125 of this joint proxy statement/prospectus for more information about the lawsuits related to the merger that has been filed. Lawsuits challenging the merger could prevent the merger from being completed, or could result in a material delay in, or the abandonment of, the merger.

One of the conditions to completion of the merger is the absence of any law or judgment issued by any court or tribunal of competent jurisdiction that prevents, makes illegal or prohibits the closing of the merger. Accordingly, if a plaintiff is successful in obtaining a judgment prohibiting completion of the merger, then such judgment may prevent the merger from being completed, or from being completed within the expected time frame.

Risk Factors Relating to Potlatch Following the Merger

Potlatch is expected to incur substantial expenses related to the integration of Deltic.

Potlatch is expected to incur substantial expenses in connection with the integration of the business, policies, procedures, operations, technologies and systems of Deltic with those of Potlatch. There are a large number of systems that must be integrated, including management information, purchasing, accounting and finance, sales, billing, payroll and benefits, fixed asset and lease administration systems and regulatory compliance. While Potlatch has assumed that a certain level of expenses would be incurred, there are a number of

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factors beyond its control that could affect the total amount or the timing of all of the expected integration expenses. Moreover, many of the expenses that will be incurred, by their nature, are difficult to estimate accurately at the present time. These expenses could, particularly in the near term, exceed the savings that Potlatch expects to achieve from the elimination of duplicative expenses and the realization of economies of scale and cost savings and synergies related to the integration of the businesses following the completion of the merger. These integration expenses likely will result in Potlatch taking significant charges against earnings following the completion of the merger, but the amount and timing of such charges are uncertain at present.

Following the merger, the combined company may be unable to integrate successfully the businesses of Potlatch and Deltic and realize the anticipated benefits of the merger.

The merger involves the combination of two companies which currently operate as independent public companies. The combined company will be required to devote significant management attention and resources to integrating its business practices and operations. The combined company may fail to realize some or all of the anticipated benefits of the merger if the integration process takes longer than expected or is more costly than expected. Potential difficulties the combined company may encounter in the integration process include the following:

In addition, Potlatch and Deltic have operated and, until the completion of the merger, will continue to operate, independently. It is possible that the integration process could result in the diversion of each company’s management’s attention, the disruption or interruption of, or the loss of momentum in, each company’s ongoing businesses or inconsistencies in standards, controls, procedures and policies, any of which could adversely affect our ability to maintain relationships with customers, suppliers and employees or our ability to achieve the anticipated benefits of the merger, or could reduce the earnings or otherwise adversely affect the business and financial results of the combined company.

The market price of shares of Potlatch common stock may decline in the future as a result of the merger.

The market price of shares of Potlatch common stock may decline in the future as a result of the merger for a number of reasons, including the unsuccessful integration of Potlatch and Deltic or the failure of Potlatch to achieve the perceived benefits of the merger, including financial results, as rapidly as or to the extent anticipated by financial or industry analysts.

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Uncertainties associated with the merger may cause a loss of management personnel and other key employees of Potlatch or Deltic which could adversely affect the future business and operations of the combined company following the merger.

Potlatch and Deltic are dependent on the experience and industry knowledge of their officers and other key employees to execute their business plans and conduct operations. The combined company’s success after the merger will depend in part upon its ability to retain key management personnel and other key employees of Potlatch and Deltic. Current and prospective employees of Potlatch and Deltic may experience uncertainty about their future roles with the combined company following the merger, which may materially adversely affect the ability of each of Potlatch and Deltic to attract and retain key personnel during the pendency of the merger. Accordingly, no assurance can be given that the combined company will be able to retain key management personnel and other key employees of Potlatch and Deltic.

The merger may not be accretive and may cause dilution to Potlatch’s cash available for distribution per share, which may negatively affect the market price of shares of Potlatch common stock.

The merger is expected to deliver accretion to Potlatch’s cash available for distribution per share in the first full year after the merger, including cost synergies and excluding integration and restructuring activities. This expectation is based on preliminary estimates which may materially change, including the currently expected timing of the merger. Potlatch could also encounter additional transaction-related costs or other factors such as a delay in the closing of the merger or the failure to realize all of the benefits anticipated in the merger. Any of these factors could cause dilution to Potlatch’s cash available for distribution per share or decrease or delay the expected accretive effect of the merger and cause a decrease in the market price of shares of Potlatch common stock.

Current Potlatch stockholders and current Deltic stockholders will have a reduced ownership and voting interest in the combined company after the merger and will exercise less influence over the combined company’s management.

Current Potlatch stockholders currently have the right to vote in the election of the Potlatch board and other matters affecting Potlatch. Current Deltic stockholders currently have the right to vote in the election of the Deltic board and on other matters affecting Deltic. Immediately after the merger is completed, it is expected that current Potlatch stockholders will own approximately 65% of the outstanding shares of Potlatch common stock and current Deltic stockholders will own approximately 35% of the outstanding shares of Potlatch common stock.

As a result of the merger, current Potlatch stockholders and current Deltic stockholders will have less influence on the combined company’s management and policies than they now have on the management and policies of Potlatch and Deltic, respectively.

The unaudited pro forma financial data for Potlatch included in this joint proxy statement/prospectus are preliminary, and Potlatch’s actual financial position and operations after the merger may differ materially from the unaudited pro forma financial data included in this joint proxy statement/prospectus.

The unaudited pro forma financial data for Potlatch included in this joint proxy statement/prospectus is presented for illustrative purposes only and is not necessarily indicative of what Potlatch’s actual financial position or operations would have been had the merger been completed on the dates indicated. Potlatch’s actual results and financial position after the merger may differ materially and adversely from the unaudited pro forma financial data included in this joint proxy statement/prospectus. Further, the combined company may recognize goodwill in the merger as part of acquisition accounting. Any goodwill would be subject to annual impairment assessments and a non-cash charge may be necessary if the results of operations and cash flows are unable to support the goodwill subsequent to the merger. For more information see the sections entitled “Summary—Summary Unaudited Pro Forma Combined Condensed Financial Information” beginning on page 24 and “Unaudited Pro Forma Condensed Combined Financial Information” beginning on page 150.

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The internal financial forecasts for Potlatch and Deltic included in this joint proxy statement/prospectus reflect management estimates and Potlatch’s and Deltic’s actual performance may differ materially from the internal financial forecasts included in this joint proxy statement/prospectus.

The internal financial forecasts for Potlatch and Deltic included in this joint proxy statement/prospectus were prepared based on information Potlatch and Deltic, as applicable, had at the time of preparation and reflect factors and assumptions that are subject to change and do not necessarily reflect current factors and assumptions that Potlatch’s or Deltic’s management, as applicable, may have about their respective businesses. As a result, actual results may differ materially from these internal financial forecasts. The inclusion of these internal forecasts in this joint proxy statement/prospectus should not be regarded as an indication that Potlatch, Deltic or any other recipient of the financial forecasts considered, or now considers, these forecasts to be material or predictive of future results.

While presented with numeric specificity, these internal financial forecasts were based on numerous variables and assumptions that are inherently uncertain and may be beyond the control of Potlatch and Deltic. Important factors that may affect actual results and cause the internal financial forecasts to not be achieved include risks and uncertainties relating to Potlatch’s and Deltic’s businesses, industry performance, commodity price trends, the regulatory environment, general business and economic conditions, tariffs, quotas and trade agreements and other factors described under the sections entitled “Cautionary Statement Regarding Forward-Looking Statements” beginning on page 26 and “Risk Factors” beginning on page 28 and in Potlatch’s and Deltic’s respective Annual Report on Form 10-K for the fiscal year ended December 31, 2016, as updated by any subsequent Quarterly Reports on Form 10-Q, all of which are filed with the SEC and are incorporated by reference into this joint proxy statement/prospectus. Since the forecasts cover multiple years, this information by its nature becomes less meaningful and predictive with each successive year.

The internal financial forecasts were not prepared for the purpose of public disclosure, nor were they prepared in compliance with published guidelines of the SEC, the guidelines established by the American Institute of Certified Public Accountants for preparation and presentation of financial forecasts, or GAAP. No independent registered public accounting firm has examined, compiled or otherwise performed any procedures with respect to these internal financial forecasts. The reports of the independent registered public accounting firms incorporated by reference into this joint proxy statement/prospectus relate to Potlatch’s and Deltic’s historical financial information and do not extend to these internal financial forecasts and should not be read to do so. These internal financial forecasts were based on internal management reporting that may differ from Potlatch’s and Deltic’s external public reporting.

None of Potlatch, Deltic or their respective affiliates, advisors, officers, directors or other representatives can provide any assurance that actual results will not differ from these internal financial forecasts, and none of them undertakes any obligation to update, or otherwise revise or reconcile, these internal financial forecasts to reflect circumstances existing after the time of preparation or to reflect the occurrence of subsequent events even in the event that any or all of the factors or assumptions underlying the forecasts are shown to be in error. For more information see the sections entitled “The Issuance of Potlatch Shares and the Adoption of the Merger Agreement—Certain Potlatch Forecasts” beginning on page 121 and “—Certain Deltic Forecasts” beginning on page 123.

Potlatch’s future results will suffer if the combined company does not effectively manage its expanded operations following the merger.

Following the merger, the size of the business of the combined company will increase significantly beyond the current size of either Potlatch’s or Deltic’s current businesses. In addition, the combined company may continue to expand its operations through additional acquisitions or other strategic transactions. Potlatch’s future success depends, in part, upon its ability to manage its expanded business, which may pose substantial challenges for management, including challenges related to the management and monitoring of new operations and

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associated increased costs and complexity. There can be no assurances that the combined company will be successful or that it will realize the expected economies of scale, synergies and other benefits currently anticipated from the merger or anticipated from any additional acquisitions or strategic transactions.

Potlatch cannot assure you that it will be able to continue paying dividends as announced.

As noted elsewhere in this joint proxy statement/prospectus, Potlatch has announced that beginning in the fourth quarter of 2017, it has increased its annual dividend from $1.50 per share to $1.60 per share. However, you should be aware that Potlatch stockholders may not receive the same dividends following the merger for reasons that may include any of the following factors:

Potlatch’s stockholders should be aware that they have no contractual or other legal right to dividends.

The shares of Potlatch common stock to be received by Deltic stockholders as a result of the merger will have different rights from the shares of Deltic common stock currently held by Deltic stockholders.

Upon completion of the merger, Deltic stockholders will become Potlatch stockholders and their rights as stockholders will be governed by the DGCL and Potlatch’s Second Restated Certificate of Incorporation (referred to as the “Potlatch certificate of incorporation”) and Potlatch’s Bylaws (referred to as the “Potlatch bylaws”). The rights associated with shares of Potlatch common stock are different from the rights associated with shares of Deltic common stock. See the section entitled “Comparison of Rights of Potlatch Stockholders and Deltic Stockholders” beginning on page 168 for a discussion of the different rights associated with shares of Potlatch common stock.

The credit ratings of the combined company or its subsidiaries may be different from what the companies currently expect.

Potlatch has evaluated the expected credit rating of the combined company and anticipates that the combined company will continue to maintain Potlatch’s current credit rating, including following any incurrence of new indebtedness in connection with refinancing indebtedness of Deltic. Potlatch’s credit ratings impact the cost and availability of future borrowings, and, as a result, Potlatch’s cost of capital. Potlatch’s ratings reflect each rating organization’s opinion of Potlatch’s financial strength, operating performance and ability to meet Potlatch’s debt obligations. Each of the ratings organizations reviews Potlatch’s ratings periodically, and there can be no assurance that Potlatch’s current ratings will be maintained in the future. Any future downgrades in Potlatch’s ratings could adversely affect Potlatch’s businesses, cash flows, financial condition and operating results.

Potlatch faces intense competition in its markets, and the failure to compete effectively could have a material adverse effect on its business, financial condition and results of operations.

Potlatch competes with North American producers, some of which may have greater financial resources and lower production costs than Potlatch does. The principal basis for competition for many of Potlatch’s products is selling price. Potlatch’s ability to maintain satisfactory margins depends in large part on Potlatch’s ability to control its costs. To the extent that one or more of Potlatch’s competitors become more successful with respect to

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any key competitive factor, Potlatch’s ability to attract and retain customers could be materially adversely affected. If Potlatch is unable to compete effectively, such failure could have a material adverse effect on its business, financial condition and results of operations.

Historically, Canada has been a significant source of lumber for the U.S. market, particularly in the new home construction market. After years of trade disputes over Canadian lumber imports, the U.S. and Canada executed a definitive agreement establishing a system of tiered taxes and/or volume restrictions relating to Canadian lumber imports to the U.S. However, this agreement expired in October 2015 and it is uncertain when or if a new agreement will be reached, and if reached what the terms of a new agreement would be. Moreover, even if a new agreement is reached, there can be no assurance that it will at all times, or at any time, effectively create a fair trade environment. Therefore, downward pressure on domestic timber and lumber prices caused by Canadian imports could continue or increase.

Other Risk Factors of Potlatch and Deltic

Potlatch’s and Deltic’s businesses are and will be subject to the risks described above. In addition, Potlatch and Deltic are, and will continue to be, subject to the risks described in Potlatch’s Annual Report on Form 10-K for the fiscal year ended December 31, 2016 and Deltic’s Annual Report on Form 10-K for the fiscal year ended December 31, 2016, respectively, in each case, as updated by any subsequent Quarterly Reports on Form 10-Q, all of which are filed with the SEC and are incorporated by reference into this joint proxy statement/prospectus. See the section entitled “Where You Can Find More Information” beginning on page 188 for the location of information incorporated by reference in this joint proxy statement/prospectus.

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The Companies

Potlatch Corporation

Potlatch Corporation

601 West First Avenue; Suite 1600

Spokane, Washington 99201

Telephone: (509) 835-1500

Potlatch Corporation (“Potlatch”), formerly known as Potlatch Holdings, Inc., was incorporated Delaware as a Real Estate Investment Trust (“REIT”). Potlatch is the successor to the business of the original Potlatch Corporation, which was incorporated in Maine in 1903. Potlatch has approximately 1.4 million acres of timberland in Alabama, Arkansas, Idaho, Minnesota and Mississippi. Potlatch also conducts a land sales and development business and operates saw mills in Arkansas, Idaho, Michigan and Minnesota and one plywood manufacturing facility in Idaho through its taxable REIT subsidiary Potlatch is headquartered in Spokane, Washington. In 2016 Potlatch generated approximately $599 million in revenue and as of December 31, 2016 had 953 employees.

Potlatch’s common stock is listed on Nasdaq under the symbol “PCH”.

Additional information about Potlatch and its subsidiaries is included in documents incorporated by reference in this joint proxy statement/prospectus. See the section entitled “Where You Can Find More Information” beginning on page 188.

Deltic Timber Corporation

Deltic Timber Corporation

210 East Elm Street, P.O. Box 7200

El Dorado, Arkansas 71731-7200

Telephone: (870) 881-9400

Deltic Timber Corporation (“Deltic”) was incorporated in Delaware in 1996 and is a vertically integrated natural resources company engaged primarily in the growing and harvesting of timber and the manufacture and marketing of lumber and medium density fiberboard. Deltic owns approximately 530,000 acres of timberland, mainly in Arkansas and north Louisiana, stocked principally with Southern Pine, known in the industry as a type of “softwood.” Deltic operates two lumber sawmills and one medium density fiberboard plant, all located in Arkansas near Deltic’s timberlands. In addition to its timber, lumber, and medium density fiberboard operations, Deltic is engaged in real estate development in central Arkansas. Deltic is headquartered in El Dorado, Arkansas, and its operations are located primarily in Arkansas and north Louisiana. In 2016, Deltic generated approximately $219 million in net sales, and as of January 31, 2017, Deltic had 547 employees.

Deltic’s common stock is listed on the NYSE under the symbol “DEL”.

Additional information about Deltic and its subsidiaries is included in documents incorporated by reference in this joint proxy statement/prospectus. See the section entitled “Where You Can Find More Information” beginning on page 188.

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Date, Time and Place

The special meeting of Potlatch stockholders will be held at 9:00 a.m. local time, on February 20, 2018 at Potlatch corporate headquarters, 601 West First Avenue, Suite 1600, Spokane, Washington 99201 unless adjourned or postponed to a later date or time.

Purpose of the Potlatch Special Meeting

At the Potlatch special meeting, Potlatch stockholders will be asked:

Recommendation of the Potlatch Board

At its meeting on October 22, 2017, the Potlatch board unanimously (1) approved and adopted the merger agreement, (2) approved the merger upon the terms and subject to the conditions set forth in the merger agreement and (3) approved the issuance by Potlatch of 1.80 shares of Potlatch common stock per share of Deltic common stock pursuant to and in accordance with the terms and conditions of the merger agreement.

Accordingly, the Potlatch board unanimously recommends that the Potlatch stockholders vote “FOR” each of the share issuance proposal and the Potlatch adjournment proposal.

Potlatch Record Date; Stockholders Entitled to Vote

Only holders of record of shares of Potlatch common stock as of the close of business on January 17, 2018, the record date for the Potlatch special meeting, will be entitled to notice of, and to vote at, the Potlatch special meeting and any adjournments or postponements of the Potlatch special meeting. A list of stockholders of record entitled to vote at the Potlatch special meeting will be available beginning 10 days prior to the Potlatch special meeting, and continuing through the Potlatch special meeting, at Potlatch’s executive offices and principal place of business at 601 West First Avenue, Suite 1600, Spokane, Washington 99201 for inspection by stockholders during ordinary business hours for any purpose germane to the Potlatch special meeting. The list will also be available at the Potlatch special meeting for examination by any stockholder of record present at the Potlatch special meeting.

As of the close of business on the record date for the Potlatch special meeting, there were outstanding a total of approximately 40,611,991 shares of Potlatch common stock entitled to vote at the Potlatch special meeting.

Quorum

A quorum is necessary to transact business at the Potlatch special meeting. Stockholders who hold at least a majority of the issued and outstanding shares of Potlatch common stock as of the close of business on the record date and who are entitled to vote must be present or represented by proxy in order to constitute a quorum for the transaction of business at the Potlatch special meeting. Abstentions and “broker non-votes” (shares held by banks, brokers or other holders of record that are present, in person or by proxy, at the Potlatch special meeting but with respect to which the bank, broker or other holder of record is not instructed by the beneficial owner of

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such shares how to vote on a particular proposal and the bank, broker or other holder of record does not have discretionary voting power on such proposal) will be counted as present for purposes of determining the presence of a quorum.

Required Vote

Approval of the share issuance proposal and the Potlatch adjournment proposal requires that votes cast “FOR” exceed the votes cast “AGAINST” each proposal (with abstentions and broker non-votes not considered votes cast.

Abstentions and Broker Non-Votes

The following will not be considered votes cast and will not count towards the approval of the share issuance proposal or the Potlatch adjournment proposal:

Voting Information

You may vote your shares in one of several ways, depending how you own your shares of common stock.

If you are a Potlatch stockholder of record (that is, if your shares are registered in your own name with Potlatch’s transfer agent), you can vote any one of four ways:

If a proxy is returned without an indication as to how the shares of Potlatch common stock represented are to be voted with regard to a particular proposal, the shares of Potlatch common stock represented by the proxy will be voted in favor of each such proposal. As of the date of this joint proxy statement/prospectus, Potlatch management has no knowledge of any business that will be presented for consideration at the Potlatch special meeting and which would be required to be set forth in this joint proxy statement/prospectus or the related Potlatch proxy card other than the matters set forth in Potlatch’s Notice of Special Meeting of Stockholders. If any other matter is properly presented at the Potlatch special meeting for consideration, it is intended that the persons named in the enclosed form of proxy and acting thereunder will vote in accordance with their best judgment on such matter.

If you are a beneficial owner of shares held in street name (that is, if you hold your shares through a bank, broker or other holder of record), you should follow the voting instructions you receive from the holder of record to vote your shares. The bank, broker or other holder of record must receive explicit voting instructions from you

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to be able to vote on the share issuance proposal and the Potlatch adjournment proposal, each of which is considered to be non-routine under the applicable rules of the Nasdaq. Banks, brokers and other holders of record do not have discretion to vote on non-routine matters unless the beneficial owner of the shares has given explicit voting instructions. Consequently, if you do not give your bank, broker or other holder of record explicit instructions, your shares will not be voted on the share issuance proposal or the Potlatch adjournment proposal and will be considered “broker non-votes” on these proposals.

Please note that if your shares are held in street name, and you wish to vote in person at the Potlatch special meeting, you must bring to the special meeting a “legal proxy” executed in your favor from the record holder (your bank, broker or other holder of record) of the shares authorizing you to vote at the Potlatch special meeting.

Your vote is very important. Accordingly, whether or not you expect to attend the Potlatch special meeting in person, we urge you to vote your shares as promptly as possible.

How Proxies Are Counted

All shares represented by properly executed proxies received in time for the Potlatch special meeting will be voted at the special meeting in the manner specified by the stockholder giving those proxies. Properly executed proxies that do not contain voting instructions with respect to the share issuance proposal or the Potlatch adjournment proposal will be voted “FOR” that proposal.

Participants in Benefit Plans

If you hold shares of Potlatch common stock in the Potlatch Hourly Company 401(k) or the Potlatch Salaried 401(k) Plan (referred to as the “Plans”), you can vote any one of four ways:

We must receive your voting instructions by 11:59 p.m. Eastern Time, on February 15, 2018 in order to tabulate the voting instructions of Plans participants who have voted and communicate those to the Plans trustee, who will ultimately vote your shares. If the proxy card is signed and returned without specific instructions for voting, or if the proxy card received by the Plans trustee is not signed or if the proxy card is not received by the Trustee, you will be treated as directing the Plans trustee to vote your shares of Potlatch common stock held in the Plans in the same proportion as the shares of Potlatch common stock for which the Trustee has received timely instructions from other participants in the Plans, unless to do so would be inconsistent with Title I of the Employee Retirement Income Security Act of 1974.

Revocation of Proxies

You have the right to revoke your proxy at any time before your shares are voted by proxy at the Potlatch special meeting. You may revoke your proxy by delivering a signed statement to Potlatch’s Corporate Secretary at or prior to the Potlatch special meeting or by timely executing and delivering, by Internet, telephone, mail or in person at the Potlatch special meeting, another proxy dated as of a later date.

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If shares are held in Potlatch Hourly or Salaried 401K Plans you may revoke your proxy by telephone by calling 1-800-690-6903 and following instructions or via Internet by going to www.proxyvote.com and following instructions.

If your shares are held in “street name” by your bank, broker or other holder of record, you should contact your bank, broker or other holder of record to change your vote or revoke your proxy.

Attending the Potlatch Special Meeting

Attendance at the Potlatch special meeting is limited to holders of shares of Potlatch common stock. If you are a stockholder of record and you plan to attend the Potlatch special meeting, please be prepared to provide proper photo identification, such as a driver’s license. If you are a street name stockholder and you plan to attend the Potlatch special meeting, you must present proof of your ownership of shares of Potlatch common stock as of the record date for the Potlatch special meeting. Acceptable proof would be an original bank or brokerage account statement as of the record date. You also must present photo identification to be admitted. If you arrive at the meeting without proof of your ownership of shares of Potlatch common stock as of the record date or without proper photo identification, you will not be admitted to the meeting.

If you are a street name stockholder and you wish to vote in person at the Potlatch special meeting, you must also bring to the Potlatch special meeting a “legal proxy” executed in your favor from the record holder (your bank, broker or other holder of record) of the shares authorizing you to vote at the Potlatch special meeting.

If you are hearing impaired or require other special accommodations due to disability, please contact Potlatch’s Corporate Secretary prior to the meeting to indicate the accommodations that you will need. No banners, placards, signs, literature for distribution, cameras, recording equipment, electronic devices, large bags, briefcases or packages will be permitted in the Potlatch special meeting.

Tabulation of Votes

Potlatch has appointed Lorrie D. Scott, Potlatch’s Vice President, General Counsel and Corporate Secretary, to serve as the inspector of election for the Potlatch special meeting. The inspector of election will, among other matters, determine the number of shares represented at the Potlatch special meeting to confirm the existence of a quorum, determine the validity of all proxies and ballots and certify the results of voting on all proposals submitted to Potlatch stockholders.

Solicitation of Proxies

In accordance with the merger agreement, the cost of proxy solicitation for the Potlatch special meeting will be borne by Potlatch. In addition to the use of the mail, proxies may be solicited by officers and directors and other employees of Potlatch, some of whom may be considered participants in the solicitation, without additional remuneration, by personal interview, telephone, facsimile or otherwise. Potlatch will also request brokerage firms, nominees, custodians and fiduciaries to forward proxy materials to the beneficial owners of shares held of record on the record date and will provide customary reimbursement to such firms for the cost of forwarding these materials. Potlatch and Deltic have jointly retained Georgeson LLC to assist in solicitation of proxies for a fee of approximately $24,000, plus reasonable expenses, for these services.

Voting by Potlatch Directors and Executive Officers

As of the close of business on the record date for the Potlatch special meeting, approximately 1.5% of the outstanding shares of Potlatch common stock were held by Potlatch directors and executive officers and their affiliates. We currently expect that Potlatch’s directors and executive officers will vote their shares in favor of the above-listed proposals, although none of them has entered into any agreements obligating him or her to do so.

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Adjournments

If a quorum is not present or represented, the stockholders entitled to vote at the Potlatch special meeting, present in person or represented by proxy, shall have power to adjourn the Potlatch special meeting from time to time, without notice other than announcement at the Potlatch special meeting, until a quorum is present or represented. If a quorum is present at the Potlatch special meeting but there are not sufficient votes at the time of the Potlatch special meeting to approve the share issuance proposal, then Potlatch stockholders may be asked to vote on the Potlatch adjournment proposal. No notices of an adjourned meeting need be given unless the adjournment is for more than 30 days or, if after the adjournment, a new record date is fixed for the adjourned meeting, in which case a notice of the adjourned meeting will be given to each stockholder of record entitled to vote at the Potlatch special meeting. At any subsequent reconvening of the Potlatch special meeting at which a quorum is present, any business may be transacted that might have been transacted at the original meeting and all proxies will be voted in the same manner as they would have been voted at the original convening of the Potlatch special meeting, except for any proxies that have been effectively revoked or withdrawn prior to the time the proxy is voted at the reconvened meeting.

Assistance

If you need assistance in completing your proxy card or have questions regarding the Potlatch special meeting, please contact Georgeson LLC at 1290 Avenue of the Americas, 9th Floor, New York, New York 10104, toll-free at (888) 565-5423.

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Date, Time and Place

The special meeting of Deltic stockholders will be held at Deltic corporate headquarters, 210 East Elm Street, El Dorado, Arkansas 71730, on February 20, 2018 at 11:00 a.m., local time, unless adjourned or postponed to a later date or time.

Purpose of the Deltic Special Meeting

At the Deltic special meeting, Deltic stockholders will be asked:

Recommendation of the Deltic Board

After careful consideration, the Deltic board, on October 21, 2017, unanimously determined that the merger agreement and the transactions contemplated by the merger agreement were advisable and in the best interests of Deltic and its stockholders and approved the merger agreement and the transactions contemplated by the merger agreement, including the merger.

Accordingly, the Deltic board unanimously recommends that Deltic stockholders vote “FOR” each of the merger proposal, the Deltic adjournment proposal and the compensation proposal.

Deltic Record Date; Stockholders Entitled to Vote

Only holders of record of shares of Deltic common stock as of the close of business on January 17, 2018, the record date for the Deltic special meeting, will be entitled to notice of, and to vote at, the Deltic special meeting and any adjournments or postponements of the Deltic special meeting. A list of stockholders of record of Deltic entitled to vote at the Deltic special meeting will be available for 10 days before the Deltic special meeting at Deltic’s executive offices and principal place of business at 210 East Elm Street, El Dorado, Arkansas 71730 for inspection by stockholders during ordinary business hours for any purpose germane to the Deltic special meeting. The list will also be available at the Deltic special meeting for examination by any stockholder of record present at the special meeting.

As of the close of business on the record date for the Deltic special meeting, there were outstanding a total of approximately 12,194,816 shares of Deltic common stock entitled to vote at the Deltic special meeting.

Quorum

A quorum is necessary to transact business at the Deltic special meeting. Stockholders who hold at least a majority of the issued and outstanding shares of Deltic common stock as of the close of business on the record date and who are entitled to vote must be present or represented by proxy in order to constitute a quorum for the transaction of business at the Deltic special meeting. Shares of Deltic common stock represented at the Deltic

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special meeting but not voted, including shares for which a stockholder directs an “abstention” from voting, will be counted as present for purposes of establishing a quorum. Broker non-votes (shares held by banks, brokers or other holders of record that are present, in person or by proxy, at the Deltic special meeting but with respect to which the bank, broker or other holder of record is not instructed by the beneficial owner of such shares how to vote on a particular proposal and the bank, broker or other holder of record does not have discretionary voting power on such proposal) will be counted as present for purposes of determining the presence of a quorum.

Required Vote

Approval of the merger proposal requires the affirmative vote of the holders of a majority of the issued and outstanding shares of Deltic common stock entitled to vote at the Deltic special meeting. Approval of the Deltic adjournment proposal and the compensation proposal each requires that votes cast “FOR” exceed the votes cast “AGAINST” each proposal (with abstentions and broker non-votes not considered votes cast).

Abstentions and Broker Non-Votes

If you fail to vote, fail to instruct your bank, broker or other holder of record to vote, or vote to abstain, it will have the same effect as a vote against the merger proposal. If you fail to vote, fail to instruct your bank, broker or other holder of record to vote, or mark your proxy or voting instructions to abstain, it will have no effect on the Deltic adjournment proposal or the compensation proposal, assuming that a quorum is present.

Voting Options

If you are a Deltic stockholder of record (that is, if your shares are registered in your own name with Deltic’s transfer agent), you can vote any one of four ways:

Voting in Person

If you plan to attend the Deltic special meeting and wish to vote in person, you will be given a ballot at the special meeting. Please note, however, that if your shares are held in “street name”, and you wish to vote at the special meeting, you must bring to the special meeting a “legal proxy” executed in your favor from the record holder (your bank, broker or other holder of record) of the shares authorizing you to vote at the special meeting. In addition, if you are a registered stockholder, please be prepared to provide proper identification, such as a driver’s license or passport. If you hold your shares in “street name”, you will need to provide proof of ownership, such as a recent account statement or letter from your bank, broker or other holder of record proving ownership on the Deltic record date, along with proper identification. Stockholders will not be allowed to use cameras, recording devices and other similar electronic devices at the meeting.

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Voting of Proxies

A proxy card is enclosed for your use. Deltic requests that you mark, sign and date the accompanying proxy and return it promptly in the enclosed postage-paid envelope. When the accompanying proxy is returned properly executed, the shares of Deltic common stock represented by it will be voted at the Deltic special meeting or any adjournment thereof in accordance with the instructions contained in the proxy.

If a proxy is returned without an indication as to how the shares of Deltic common stock represented are to be voted with regard to a particular proposal, the Deltic common stock represented by the proxy will be voted in favor of each such proposal. As of the date of this joint proxy statement/prospectus, Deltic management has no knowledge of any business that will be presented for consideration at the Deltic special meeting and which would be required to be set forth in this joint proxy statement/prospectus or the related Deltic proxy card other than the matters set forth in Deltic’s Notice of Special Meeting of Stockholders. If any other matter is properly presented at the Deltic special meeting for consideration, it is intended that the persons named in the enclosed form of proxy and acting thereunder will vote in accordance with their best judgment on such matter.

Your vote is very important. Accordingly, whether or not you plan to attend the Deltic special meeting in person, we urge you to vote your shares as promptly as possible.

How Proxies Are Counted

All shares represented by properly executed proxies received in time for the Deltic special meeting will be voted at the meeting in the manner specified by the stockholder giving those proxies. Properly executed proxies that do not contain voting instructions with respect to the merger proposal, the Deltic adjournment proposal or the compensation proposal will be voted “FOR” that proposal.

Shares Held in “Street Name”

If you hold your shares in a stock brokerage account or if your shares are held by a bank, broker or other holder of record (that is, in street name), you must provide the bank, broker or other holder of record of your shares with instructions on how to vote your shares if you wish them to be counted. Please follow the voting instructions provided by your bank, broker or other holder of record. Please note that you may not vote shares held in street name by returning a proxy card directly to Deltic or by voting in person at your special meeting unless you provide a “legal proxy”, which you must obtain from your bank, broker or other holder of record. Further, banks, brokers or other holders of record who hold shares of Deltic common stock on behalf of their customers may not give a proxy to Deltic to vote those shares without specific instructions from their customers.

If you do not instruct your broker on how to vote your shares of Deltic common stock, your bank, broker or other holder of record may not vote your shares, which will have the same effect as a vote against the merger proposal. If you do not instruct your broker on how to vote your shares of Deltic common stock, it will have no effect on the Deltic adjournment proposal and the compensation proposal, assuming that a quorum is present.

Revocation of Proxies

You have the power to revoke your proxy at any time before your proxy is voted at the Deltic special meeting. You can revoke your proxy in one of four ways:

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If your shares are held in “street name” by your bank, broker or other holder of record, you should contact your bank, broker or other holder of record to change your vote or revoke your proxy.

Tabulation of Votes

Deltic has appointed one or more representatives of Deltic, who will be assisted by Computershare, Inc., as proxy tabulation agent, to serve as the inspector of election for the Deltic special meeting. The inspector of election will, among other matters, determine the number of shares represented at the Deltic special meeting to confirm the existence of a quorum, determine the validity of all proxies and ballots and certify the results of voting on all proposals submitted to the Deltic stockholders.

Solicitation of Proxies

In accordance with the merger agreement, the cost of proxy solicitation for the Deltic special meeting will be borne by Deltic. In addition to the use of the mail, proxies may be solicited by officers and directors and other employees of Deltic, some of whom may be considered participants in the solicitation, without additional remuneration, by personal interview, telephone, facsimile or otherwise. Deltic will also request brokerage firms, nominees, custodians and fiduciaries to forward proxy materials to the beneficial owners of shares held of record on the record date and will provide customary reimbursement to such firms for the cost of forwarding these materials. Deltic and Potlatch have jointly retained Georgeson LLC to assist in solicitation of proxies for a fee of approximately $24,000, plus reasonable out-of-pocket expenses.

Voting by Deltic Directors and Executive Officers

As of the close of business on the record date for the Deltic special meeting, approximately 9.4% of the outstanding shares of Deltic common stock were held by Deltic directors and executive officers and their affiliates. We currently expect that Deltic’s directors and executive officers will vote their shares in favor of the above-listed proposals, although none of them has entered into any agreements obligating him or her to do so.

Adjournments

If a quorum is not present or represented, the stockholders entitled to vote at the Deltic special meeting, present in person or represented by proxy, shall have power to adjourn the Deltic special meeting from time to time, without notice other than announcement at the Deltic special meeting, until a quorum is present or represented. If a quorum is present at the Deltic special meeting but there are not sufficient votes at the time of the Deltic special meeting to approve the merger proposal, then Deltic stockholders may be asked to vote on the Deltic adjournment proposal. No notices of an adjourned meeting need be given unless the adjournment is for more than 30 days or, if after the adjournment, a new record date is fixed for the adjourned meeting, in which case a notice of the adjourned meeting will be given to each stockholder of record entitled to vote at the Deltic special meeting. At any subsequent reconvening of the Deltic special meeting at which a quorum is present, any business may be transacted that might have been transacted at the original meeting and all proxies will be voted in the same manner as they would have been voted at the original convening of the Deltic special meeting, except for any proxies that have been effectively revoked or withdrawn prior to the time the proxy is voted at the reconvened meeting.

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Assistance

If you need assistance in completing your proxy card or have questions regarding the Deltic special meeting, please contact Georgeson LLC at 1290 Avenue of the Americas, 9th Floor, New York, New York 10104, toll-free at (800) 279-6913.

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POTLATCH PROPOSAL 1 AND DELTIC PROPOSAL 1:

THE ISSUANCE OF POTLATCH SHARES AND THE ADOPTION OF THE MERGER AGREEMENT

Effects of the Merger

On the closing date, Deltic will merge with and into Merger Sub. At the effective time of the merger, the separate corporate existence of Deltic will cease and Merger Sub will continue as the surviving entity in the merger. Subject to the terms and conditions of the merger agreement, upon completion of the merger, each share of Deltic common stock issued and outstanding immediately prior to the completion of the merger (other than shares of Deltic common stock owned by Deltic as treasury stock) will be converted into the right to receive 1.80 shares of Potlatch common stock with cash paid in lieu of fractional shares. This exchange ratio is fixed and will not be adjusted for changes in the market price of either shares of Potlatch common stock or shares of Deltic common stock prior to the merger.

Background of the Merger

The Deltic board and management regularly review Deltic’s performance, prospects and strategy, as well as developments in the forest products and real estate industries, opportunities and challenges facing participants in those industries and opportunities to increase stockholder value. In addition, Deltic regularly engages with its stockholders to understand their perspectives on the most effective ways to increase stockholder value, and from time to time, certain of Deltic’s stockholders have suggested that Deltic explore one or more possible business combination transactions.

The Potlatch board and management regularly review Potlatch’s performance, prospects and strategy in light of the current business and economic environment, as well as developments in the timber industry and opportunities and challenges facing participants in that industry. These reviews have included consideration, from time to time, of potential strategic alternatives, including strategic acquisitions and divestitures, business combination transactions and remaining an independent, standalone entity.

On October 10, 2016, the board of directors of Deltic announced the retirement of Ray C. Dillon as Deltic’s long-time President and Chief Executive Officer, and the election of D. Mark Leland, a member of the Deltic board of directors, as interim President and Chief Executive Officer. In the period following the leadership change, Mr. Leland and Robert C. Nolan, Chairman of the board of directors of Deltic, received outreach from certain other companies engaged in the forest products industry, particularly Potlatch and a company referred to as “Party A”, expressing a potential interest in a business combination with Deltic.

From time to time during the period from when Mr. Leland was named interim President and Chief Executive Officer to the time the merger agreement with Potlatch was entered into, Deltic received input from a number of stockholders, particularly Southeastern Asset Management Inc. (“SEAM”), its largest stockholder, regarding their views based on publicly available information and information available from sources other than Deltic as to the courses of action those stockholders considered to be in the best interests of Deltic. Also during this period, Deltic received inquiries from several parties potentially interested in purchasing certain portions of Deltic’s assets such as its sawmills or its medium density fiberboard manufacturing operations, including an indication of interest from a third party with respect to the acquisition of Deltic’s manufacturing business for $200 million. None of these inquiries resulted in substantive discussions regarding a transaction.

Following Deltic’s October 10, 2016 announcement of the retirement of its long-time chief executive officer, Michael J. Covey, Potlatch’s chairman and chief executive officer, called a representative of Goldman Sachs to inquire about approaching Mr. Nolan regarding Potlatch’s possible interest in a merger. A representative of Goldman Sachs spoke to Mr. Nolan and was told that Deltic planned to focus on its search for a new Chief Executive Officer. Goldman Sachs had served as Deltic’s financial advisor since September 2012 on several projects and although Goldman Sachs had not yet been specifically retained to assist with a potential strategic transaction, they assisted Deltic with the initial stages of the process pursuant to the earlier arrangements.

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On December 2, 2016, the Potlatch board held a regular meeting. Mr. Covey discussed a potential combination with Deltic, and the Potlatch board authorized Mr. Covey to explore the possibility of a transaction with Deltic.

On January 9, 2017, Mr. Covey updated the Potlatch board about Potlatch’s interest in Deltic and related activities. Mr. Covey requested that the directors review a management presentation on a possible combination with Deltic that had been provided to the Potlatch board.

On January 11, 2017, the Potlatch board held a telephonic meeting to review the management presentation on Deltic and to discuss a possible combination with Deltic. Mr. Covey and Eric J. Cremers, Potlatch’s president and chief operating officer, provided an overview of Deltic, including its timberland, manufacturing, real estate and management, and summarized Deltic’s recent results of operations and stock performance. They discussed several opportunities to improve Deltic’s operations and financial returns. They also reviewed different valuation approaches, based on base case and enhanced synergy assumptions, outlined a range of values for Deltic and requested authority to proceed to explore a possible transaction with Deltic. The Potlatch board authorized management to begin to explore a combination, including engagement of a financial advisor.

On January 13, 2017, at the direction of Potlatch management, a representative of BofA Merrill Lynch had a telephone conversation with a representative of Goldman Sachs, who agreed to contact Mr. Nolan and Mr. Leland regarding Potlatch’s interest.

On January 17, 2017, at the direction of Deltic management, a representative of Goldman Sachs reported to a representative of BofA Merrill Lynch that Deltic’s Chief Executive Officer search was in the advanced stages. At the direction of Potlatch management, the representative of BofA Merrill Lynch asked a representative of Goldman Sachs to request a meeting between Potlatch and Deltic.

On January 19, 2017, Mr. Covey reported to the Potlatch board that management recommended retaining BofA Merrill Lynch as its financial advisor, described BofA Merrill Lynch’s qualifications and outlined the engagement terms with BofA Merrill Lynch.

On February 2, 2017, Messrs. Nolan and Leland met with Messrs. Covey and Cremers. At the meeting, Potlatch indicated an interest in a possible business combination transaction between Potlatch and Deltic, and Potlatch provided Deltic with background information about Potlatch as well as information from Potlatch regarding potential synergies and potential benefits to stockholders of both companies of a combination transaction between Potlatch and Deltic. Messrs. Nolan and Leland indicated to Messrs. Covey and Cremers that Deltic was focused on its process of selecting a new Chief Executive Officer and that they did not believe it was the right time for Deltic to consider a business combination transaction. No specific proposal was made at the meeting.

As a result of the outreach from Party A following the retirement of Mr. Dillon, on February 3, 2017, Messrs. Nolan and Leland met with representatives of Party A. Party A indicated that if Deltic were to be approached by another party regarding a business combination, then Deltic should consider contacting Party A at that time. Messrs. Noland and Leland indicated to the Party A representatives that Deltic was focused on its process of selecting a new Chief Executive Officer and had not been actively considering business combination transactions at that time.

On February 3, 2017, Potlatch and BofA Merrill Lynch executed an engagement letter for BofA Merrill Lynch to serve as Potlatch’s financial advisor in connection with a possible transaction with Deltic.

On February 7, 2017, at the direction of Potlatch management, representatives of BofA Merrill Lynch discussed telephonically with representatives of Goldman Sachs the information that was discussed in the February 2, 2017 meeting between the representatives of Potlatch and Deltic, including information regarding a potential business combination between Potlatch and Deltic.

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On February 16, 2017, the Deltic board held a regularly scheduled meeting. Among other things, the Deltic board discussed its annual strategic plan and Goldman Sachs gave a presentation that included a preliminary financial analysis of Deltic and a preliminary analysis of certain potential business combination transactions. The Deltic board determined that it was not yet the time to engage with either Potlatch or other potential merger partners, in part because the Deltic board wanted to retain a new Chief Executive Officer who would lead a full review of Deltic’s strategic position and opportunities to enhance value. Consequently, the Deltic board determined to continue its process for hiring a new Chief Executive Officer. At the direction of the Deltic board, representatives of Goldman Sachs communicated the Deltic board’s position to representatives of BofA Merrill Lynch.

On February 17, 2017, at a regularly scheduled Potlatch board meeting, Mr. Covey and Mr. Cremers briefed the Potlatch board on the status of discussions with Deltic and reviewed an updated Potlatch management presentation regarding a proposed combination with Deltic, including potential operational and financial benefits of the combined companies.

On February 20, 2017, a representative of SEAM contacted Mr. Nolan and indicated that he was aware that Deltic had engaged in discussions with multiple parties regarding a possible combination transaction and encouraged Deltic to announce that fact and continue the engagement.

On February 22, 2017, SEAM, which had previously been a Schedule 13G filer as a passive investor in Deltic, filed a Schedule 13D in connection with its holding in Deltic. SEAM stated in its Schedule 13D that SEAM and Deltic had been approached by “multiple parties interested in merging with or acquiring Deltic”. In the Schedule 13D, SEAM also indicated its belief that a combination with a timber REIT would be beneficial for the Deltic stockholders. Later that day, Deltic issued a press release stating that Deltic had met with representatives of SEAM and looked forward to continued, constructive dialogue with its stockholders focused on enhancing the value of Deltic. The press release also stated that the Deltic board was committed to acting in the best interests of Deltic stockholders, and regularly reviews its strategic priorities and opportunities to enhance value.

On February 23, 2017, the Deltic board held a special meeting to discuss Deltic’s search for a new Chief Executive Officer. After consideration of various factors, including his strategic expertise and his experience in business combination transactions, the board unanimously voted to offer the position of Chief Executive Officer to John D. Enlow, Sr.

On February 27, 2017, Deltic announced the appointment of Mr. Enlow as President and Chief Executive Officer of Deltic, to be effective on March 8, 2017. Deltic also announced that the then-current Chief Financial Officer had been terminated and that Byrom L. Walker had been named as interim Chief Financial Officer of Deltic.

On March 7, 2017, Mr. Covey reviewed with the Potlatch board Potlatch’s preliminary proposal for an all-stock merger with Deltic at an exchange ratio between 1.84 and 1.93 shares of Potlatch common stock for each share of Deltic common stock.

On March 8, 2017, Potlatch submitted a letter to Deltic indicating Potlatch’s interest in a transaction between Potlatch and Deltic. The letter outlined a preliminary non-binding proposal for a stock-for-stock merger whereby Deltic’s stockholders would receive 1.839 – 1.930 shares of Potlatch common stock for every share of Deltic common stock. Based on closing stock prices as of March 6, 2017, the proposal implied an offer price of $81.00—$85.00 per share of Deltic common stock. Potlatch noted that its indication of interest was based on publicly available information only and that it would need to conduct a full due diligence review before it could make a binding offer.

On March 20, 2017, the Deltic board held a special meeting to review Potlatch’s indication of interest. At the invitation of the Deltic board, representatives of Davis Polk, Deltic’s outside counsel, and Goldman Sachs

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were present. Davis Polk reviewed with the Deltic board the directors’ fiduciary duties and other legal matters relating to the consideration of a potential strategic transaction. Goldman Sachs discussed, among other things the financial terms of the preliminary non-binding indication of interest from Potlatch. Mr. Enlow provided an overview of the internal valuation of Deltic that was underway, which included a valuation of each of Deltic’s operating segments. Mr. Enlow also discussed aspects of a strategic review to be conducted by Deltic during the next 60-90 days, which would include a competitive benchmarking analysis against Deltic’s peer group and the identification of opportunities to improve performance. After discussion, the Deltic board unanimously agreed that it would be in the Deltic stockholders’ best interests for Deltic to engage Potlatch in further discussion and gather more information. The Deltic board also agreed that Deltic should also continue its own internal valuation and strategic review as discussed by Mr. Enlow. Accordingly, the Deltic board authorized Mr. Enlow and Deltic’s management to engage Potlatch in further discussions and to continue Deltic’s internal valuation and strategic review.

Over the course of the ensuing months, Deltic continued to develop and analyze its strategic alternatives, which included a standalone plan that implemented strategic initiatives to become best in class, the conversion of Deltic’s C-corporation structure into a REIT structure, or a merger with a strategic partner.

On March 21, 2017, Deltic and Goldman Sachs executed an engagement letter for Goldman Sachs to serve as Deltic’s financial advisor in connection with a potential strategic transaction.

Also on March 21, 2017, representatives of Goldman Sachs contacted representatives of BofA Merrill Lynch in accordance with the instructions of the Deltic board at its March 20, 2017 board meeting, and delivered Deltic’s feedback regarding Potlatch’s March 8 written proposal. Goldman Sachs indicated that although Deltic was not conducting a sale process, the board would properly evaluate any proposal that it received. Goldman Sachs further indicated Deltic’s view that Potlatch’s proposal meaningfully undervalued the Deltic business. Goldman Sachs noted that Deltic was engaged in an internal review of its businesses. Goldman Sachs stated that in order for the parties to continue to engage and to share confidential information, the parties would need to enter into a non-disclosure agreement, and offered to provide a draft.

Following a request by SEAM for non-public information, Deltic delivered a draft non-disclosure agreement to SEAM on March 23, 2017. After discussing the proposed terms of the non-disclosure agreement, SEAM informed Deltic that it would not enter into the non-disclosure agreement.

Following the conversation between representatives of Goldman Sachs and representatives of BofA Merrill Lynch on March 31, 2017, Deltic delivered a draft non-disclosure agreement to Potlatch, and thereafter the parties negotiated the terms thereof. On April 5, 2017, Deltic and Potlatch executed a mutual non-disclosure agreement. The non-disclosure agreement contained a customary “standstill” provision, which, subject to certain exceptions, prohibited either party from acquiring shares in the other party’s common stock or taking certain other actions for a period of one year from the date of the non-disclosure agreement.

During the ensuing months, Deltic and Potlatch, with the assistance of their advisors, conducted substantial due diligence on each other including as described below.

On April 6, 2017, Mr. Cremers updated the Potlatch board on developments with Deltic.

On April 11, 2017, Potlatch and its advisors were granted access to the virtual data room developed by Deltic for the potential transaction, and Deltic and its advisors were granted access to the virtual data room developed by Potlatch for the potential transaction.

On April 17, 2017, Potlatch retained a consultant to assist with evaluation of Deltic’s timber inventory.

On April 19, 2017, representatives of each of Deltic, Potlatch, Goldman Sachs and BofA Merrill Lynch met in Dallas, Texas for due diligence discussions regarding Deltic’s and Potlatch’s businesses and financial

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projections and the potential synergies from a business combination transaction. Further, the parties discussed in general terms the potential business combination including potential corporate governance and executive leadership of the combined company.

On April 21, 2017, at the direction of Mr. Enlow, representatives of Goldman Sachs contacted the financial advisor of a company engaged in the forest products industry (referred to as “Party B”). From time to time in the first quarter of 2017, the financial advisor of Party B had reached out to Goldman Sachs to inquire regarding a potential transaction with Deltic. On April 25, 2017, Mr. Enlow spoke with the Chief Executive Officer of Party B to discuss a possible business combination transaction pursuant to which Party B, which was smaller than Deltic, would be acquired by Deltic. Over the following several weeks, representatives of Goldman Sachs and representatives of the financial advisor to Party B engaged in several discussions regarding a possible business combination transaction between the two parties. In late May 2017, Deltic determined not to continue considering a potential transaction with Party B because the transaction would likely have required Deltic stockholder approval and Deltic had concluded that in the current environment it would have been difficult to garner stockholder support of a transaction that resulted in material non-organic growth for Deltic.

On April 21, 2017, Mr. Covey updated the Potlatch board on the meeting with Deltic and reviewed topics that were presented and discussed.

On April 27, 2017, the Deltic board held a regularly scheduled meeting at which Deltic’s valuation and strategy were discussed. Mr. Enlow presented preliminary valuation estimates and strategic initiatives for Deltic derived from the ongoing exercise that had been undertaken by Deltic. The Deltic board authorized Mr. Enlow to further develop and report on these valuations and initiatives.

On May 1, 2017, the Deltic board held a special meeting to discuss the business and operations of Potlatch and the internal valuations of Deltic that were being prepared. During this meeting, Mr. Enlow noted that Deltic should expect to receive a definitive offer once Potlatch completed its analysis. The Deltic board directed Deltic management to continue discussions with Potlatch.

Over the course of the period following the April 19 meeting between representatives of Potlatch and Deltic, Potlatch and Deltic and their advisors continued to engage in general due diligence and discussed valuation methodologies and perspectives. Deltic continued to progress its comprehensive strategic review during that period and indicated to Potlatch that such review was ongoing.

On May 3, 2017, at the Potlatch board’s annual meeting, Mr. Covey and Mr. Cremers updated the Potlatch board on the status of discussions with Deltic.

On May 4, 2017, at the direction of Potlatch management, representatives of BofA Merrill Lynch requested that Goldman Sachs provide additional harvest information and responses to questions based on a review of Deltic’s financial forecasts. Representatives of Goldman Sachs responded that Deltic was working on an updated harvest schedule, expected to be completed by May 22, 2017.

On May 22, 2017, representatives of Goldman Sachs advised representatives of BofA Merrill Lynch that Deltic expected to finalize its harvest plan that week and prepare a revised financial forecast within two weeks of completion of the harvest plan and approval of the plan by the Deltic board.

On May 25, 2017, Mr. Covey updated the Potlatch board on the status of discussions with Deltic and likely timing.

On June 7, 2017, a representative of Goldman Sachs informed a representative of BofA Merrill Lynch that the Deltic board would meet on June 15, 2017 to review the new harvest plan and revised financial projections. At the direction of Potlatch management, representatives of BofA Merrill Lynch reiterated Potlatch’s request for additional information relating to Deltic’s timber inventory and responses to questions posed to Deltic’s timber consultant.

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On June 9, 2017, Mr. Covey updated the Potlatch board on timing and changes to Deltic’s latest harvest plan.

On June 15, 2017, the Deltic board held a regularly scheduled meeting at which it reviewed and discussed management’s updated reports of its valuation of Deltic and strategic alternatives for Deltic to create value for Deltic stockholders.

On June 16, 2017, a representative of Goldman Sachs informed a representative of BofA Merrill Lynch that the Deltic board had met and had approved the new financial projections. Goldman Sachs posted the new financial projections in the dataroom as well as answers to some of Potlatch’s questions regarding timber inventory.

On June 22, 2017, Potlatch requested additional data relating to Deltic’s timber inventory and manufacturing plants, and on June 27, 2017, at the direction of Potlatch management, representatives of BofA Merrill Lynch contacted representatives of Goldman Sachs about the outstanding requests from Potlatch for additional timber inventory information.

On June 28, 2017, representatives of Potlatch participated in a conference call with representatives of Deltic, as well as representatives of BofA Merrill Lynch and Goldman Sachs, to discuss questions regarding Deltic timberlands raised by Potlatch.

On July 11, 2017, representatives of Potlatch participated in a conference call with representatives of Deltic to discuss Deltic’s new financial model.

On July 13, 2017, Mr. Enlow contacted Mr. Covey and discussed Deltic’s forecasts and the reasons the forecasts Deltic had prepared were higher than Deltic’s historical performance.

On July 17, 2017, at the request of Potlatch management, a representative of BofA Merrill Lynch contacted a representative of Goldman Sachs regarding timing of submittal of an offer and asked for a commitment of a prompt Deltic board meeting to consider the Potlatch offer.

On July 19, 2017, a representative of Goldman Sachs called a representative of BofA Merrill Lynch to request that Potlatch submit its proposal on July 26, 2017.

On July 24, 2017, representatives of Deltic, representatives of Goldman Sachs, representatives of Potlatch and representatives of BofA Merrill Lynch held a due diligence call related to Potlatch’s financial model.

On July 25, 2017, Potlatch submitted to Deltic a revised non-binding proposal for a stock-for-stock merger whereby Deltic’s stockholders would receive 1.710 shares of Potlatch common stock for every share of Deltic common stock, which would result in Deltic stockholders owning approximately 34% of the combined company after the close of the transaction. Based on closing stock prices as of July 25, 2017, the non-binding proposal implied an offer price of $83.02 per share of Deltic common stock and noted that the implied offer price was the midpoint of the $81.00—$85.00 offer price range implied by Potlatch’s preliminary non-binding proposal from March 8, 2017. In the July 25 letter, Potlatch also set forth certain adjustments it had made based on its due diligence to Deltic’s management forecast. The proposal also noted that Potlatch would anticipate the board of directors of the combined company to be comprised of existing board members from both companies, with representation proportional to the respective ownership.

On August 2, 2017, Deltic issued a press release announcing its second quarter 2017 results. Deltic stated in its press release that it was assessing a comprehensive range of strategic alternatives.

On August 4, 2017, the Deltic board held a special meeting in Dallas, Texas to review the terms of the transaction outlined in the July 25, 2017 non-binding proposal from Potlatch. At the invitation of the Deltic

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board, representatives of Davis Polk and Goldman Sachs were also in attendance. Davis Polk reviewed with the Deltic board the directors’ fiduciary duties and other legal matters relating to the consideration of a potential strategic transaction. The Deltic board received management’s updated financial analysis regarding Deltic’s timberland valuation, an assessment of possible strategic alternatives and an assessment of the Potlatch proposal. Goldman Sachs discussed with the board the financial terms of the proposal from Potlatch, as well as certain of Deltic’s other strategic options, such as remaining a standalone C-corporation or converting to a standalone REIT. After discussing various considerations, the Deltic board directed Goldman Sachs to relay a counterproposal to Potlatch indicating that continued discussions of a proposed combination would be contingent upon an exchange ratio of at least 2.0 shares of Potlatch common stock for each share of Deltic common stock. The Deltic board also directed Goldman Sachs to reach out to three potential buyers that Goldman Sachs had previously identified as having a potential interest in, and the capability to consummate, a strategic transaction with Deltic, consisting of Party A and two additional forest products industry participants referred to as “Party C” and “Party D”.

On August 4, 2017, at the direction of the Deltic board, Goldman Sachs delivered a telephonic response to a representative of Potlatch indicating that Potlatch’s offer was unacceptable as constructed and that if Potlatch would like to continue to engage in meaningful discussions with Deltic, the exchange ratio would need to be at least 2.0 shares of Potlatch common stock for every share of Deltic common stock. Goldman Sachs also communicated that Deltic believed that the board composition of a combined company should consist of at least three Deltic directors out of a total of eight directors on the board, or four Deltic directors out of a total of eleven directors on the board, that Mr. Enlow should have a senior management role in the combined company, that the combined company should have a new name and that southern operations of the combined company should be headquartered in El Dorado, Arkansas.

After the August 4 board meeting, Deltic management increased its focus on developing its own standalone REIT plan.

On August 8, 2017, Mr. Covey updated the Potlatch board on Deltic’s response.

During mid-August 2017, representatives of both Goldman Sachs and BofA Merrill Lynch held multiple discussions regarding the terms of a potential business combination between Potlatch and Deltic. Also during this time, representatives of Goldman Sachs contacted Party A, Party C and Party D, the three buyers that Goldman Sachs had referenced at the August 4, 2017 Deltic board meeting.

On August 12, 2017, Potlatch lead director John Moody called Deltic director Robert Tudor III to discuss the potential transaction; Mr. Tudor reiterated that the Deltic board would not be inclined to proceed with an offer unless it reflected value superior to what Deltic could achieve on a standalone basis, and that the Deltic board believed that Potlatch’s proposal did not reflect superior value.

On August 17, 2017, Potlatch sent a letter to Deltic responding to the terms that had been conveyed by Goldman Sachs on August 4, 2017 at the direction of the Deltic board. Potlatch indicated in its letter that it was disappointed by the Deltic board’s decision to reject the August 4 offer and in the Deltic board’s position that Deltic stockholders would need to receive at least 2.0 shares of Potlatch common stock for each share of Deltic common stock, but Potlatch maintained that the combination of Potlatch and Deltic was in the best interest of the companies’ respective stockholders. The August 17 letter did not propose a revised exchange ratio or other modified financial terms.

On August 22, 2017, Deltic sent a response to Potlatch’s August 17 letter indicating that the revised non-binding proposal sent on July 25, 2017 undervalued Deltic and the proposed exchange ratio of 1.70 shares of Potlatch common stock for each share of Deltic common stock was below the range given in the March 8 letter. The letter noted that since the March 8 non-binding proposal, Deltic had developed a business improvement plan based on increased harvest levels, mill operating rates and cost reductions, all of which had been previously shared with Potlatch, and the July 25 non-binding proposal did not take the value of this plan into consideration.

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The letter further noted that the July 25 non-binding proposal reflected no premium based on Deltic’s and Potlatch’s then five, three, and one-year average share prices, the premium referenced in the July 25 proposal reflected a meaningful and unseasoned run up in Potlatch’s share price and a drop in Deltic’s share price over the preceding three months, and that a vast majority of the synergy benefits in the potential combination could be accomplished with Deltic remaining a standalone company and should not be considered as part of any premium. The letter noted that Deltic was engaging with other parties but was also open to further discussions with Potlatch.

Between August 18, 2017 and August 24, 2017, Deltic held discussions and corresponded with representatives of SEAM. During such interactions, SEAM offered to facilitate discussions with potential buyers on behalf of Deltic and requested that Deltic provide non-public information to SEAM. In order to do so, Deltic stated that SEAM would be required to enter into a customary non-disclosure agreement, which would include a customary standstill provision. After negotiations between the two parties regarding the terms of the non-disclosure agreement and discussions as to the type of information Deltic was prepared to provide to SEAM, SEAM determined that it would not execute the non-disclosure agreement and terminated discussions on the non-disclosure agreement on August 24, 2017.

On August 25, 2017, SEAM filed an amendment to its Schedule 13D filed on February 22, 2017 in connection with its holding in Deltic. SEAM stated in its Schedule 13D amendment that it had engaged in discussions with both Deltic and multiple parties interested in merging with or acquiring Deltic, and that it was aware of at least one highly reputable industry party that had made an unsolicited proposal to merge with Deltic in exchange for stock in the acquiring company. SEAM indicated that it supported this proposal and encouraged other stockholders “to express their views to the board and management for a better outcome than the status quo.”

Between August 25, 2017 and August 28, 2017, Deltic executed non-disclosure agreements with Party A, Party C and two other companies engaged in the forest products industry, referred to as “Party E” and “Party F”, and shortly thereafter the parties were granted access to a virtual data room developed by Deltic for the process. Party C and Party E had indicated to Deltic that they would be working jointly to consider a transaction with Deltic. Party A and Party F also had indicated to Deltic that they would be working jointly to consider a transaction with Deltic. In addition, by this time Party D had indicated that it was not interested in a potential transaction and declined to participate in Deltic’s process.

On August 28, 2017, Deltic issued a press release providing an update regarding its strategic alternatives process. The press release noted that after making significant progress evaluating Deltic’s assets, competitive position, and market risks and opportunities, Deltic was assessing a comprehensive range of strategic alternatives. The press release stated that over the past several months, Deltic had been approached by a number of industry participants regarding interest in a potential strategic transaction, and that Deltic had been actively engaging in evaluating those confidential indications of interests and intended to continue the process to develop potential external strategic alternatives. Additionally, the press release reiterated the Deltic board’s commitment to exploring all options, both internal and external, to maximize stockholder value. The press release also noted that Deltic had met with SEAM on a number of occasions to discuss SEAM’s ideas and that Deltic maintains open dialogue with its stockholders and values their input.

Beginning in late August, as Deltic management continued to evaluate its standalone REIT plan, the risks of that plan became more quantifiable, including risks related to the timing and execution of the plan, particularly in the event of a market downturn.

On August 30, 2017, the Potlatch board held its regular quarterly board meeting and discussed potential paths forward regarding a transaction with Deltic, including increasing the exchange ratio.

On September 6, 2017, representatives of Deltic attended an in-person meeting with representatives of Party C and Party E to discuss Deltic’s business and projections.

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On September 7, 2017, representatives of Deltic attended in-person meetings with representatives of Party A and Party F to discuss Deltic’s business and projections and Party A’s business and projections.

On September 11, 2017, at the direction of Potlatch management, a representative of BofA Merrill Lynch suggested to a representative of Goldman Sachs that Deltic and Potlatch meet if Deltic was willing to come down from an exchange ratio of 2.0 shares of Potlatch common stock for each share of Deltic common stock. A representative of Goldman Sachs updated Mr. Enlow, who consulted with Mr. Nolan and instructed Goldman Sachs to inform BofA Merrill Lynch that Deltic would consider an exchange ratio of less than 2.0 shares of Potlatch common stock for each share of Deltic common stock. The Goldman Sachs representative then informed BofA Merrill Lynch that Deltic was engaged with others in a competitive process, but that Deltic would consider an exchange ratio of less than 2.0 shares of Potlatch common stock for each share of Deltic common stock and proposed a meeting to discuss the exchange ratio as well as other aspects of a proposed combination.

On September 13, 2017, Mr. Covey informed the Potlatch board that Deltic would consider an exchange ratio below 2.0 and suggested a meeting the following week in Dallas to discuss the issues raised in earlier letters as well as the exchange ratio.

On September 13, 2017, Party C and Party E withdrew from discussions regarding a potential business combination transaction with Deltic. Party C and Party E cited concern that a market premium could not be offered as their reason for withdrawal from the process.

On September 17 and September 18, 2017, Deltic conducted due diligence meetings with Party F and Party A, respectively. No potential transaction terms were discussed during these meetings.

On September 20, 2017, Messrs. Nolan and Enlow and representatives of Goldman Sachs met with Messrs. Covey and Cremers and representatives of BofA Merrill Lynch, at the request of Potlatch. At the meeting, the parties discussed the 1.710 exchange ratio included in Potlatch’s July 25 letter proposal. Messrs. Nolan and Enlow maintained that such an exchange ratio undervalued Deltic. The parties also discussed topics such as board composition and management of the combined company, Potlatch’s vision for the combined company and the potential for increased synergies from the transaction. Later that day Mr. Covey updated the Potlatch board on the substance of the meeting.

Following this meeting, several discussions took place between the Deltic and Potlatch and/or their respective advisors on various issues, including financial projections and valuation. On September 21, 2017, Mr. Covey spoke with Mr. Moody regarding the Deltic transaction and the Potlatch board’s willingness to offer a higher exchange ratio. On September 22, 2017, representatives of Goldman Sachs and the general counsels of each of Deltic and Party A telephonically discussed legal due diligence matters and the process for next steps.

On September 23, 2017, Deltic sent to Potlatch a process letter including instructions for submitting a binding offer for a business combination with Deltic.

On September 24, 2017, at the request of Potlatch management, representatives of BofA Merrill Lynch sent representatives of Goldman Sachs a list of additional questions regarding Deltic’s financial model, and Mr. Cremers sent Mr. Enlow and Mr. Nolan questions relating to Deltic’s manufacturing business.

On September 25, 2017, Party A and Party F withdrew from discussions regarding a potential business combination transaction with Deltic. Party A and Party F cited concern that a market premium could not be offered as their reason for withdrawal from the process.

On September 26 and 27, 2017, representatives of both Goldman Sachs and BofA Merrill Lynch and representatives of Deltic and Potlatch telephonically discussed due diligence matters related to the financial projections of Deltic as well as due diligence matters related to the financial projections of Potlatch.

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On September 28, 2017, Mr. Covey spoke with Mr. Nolan to discuss timing as well as board composition and management of the combined company, including the role of Mr. Enlow.

On September 29, 2017, Mr. Covey updated the Potlatch board about a proposed agenda for a special telephonic meeting of the board to be held on October 2, 2017 relating to discussions with Deltic.

On October 2, 2017, Mr. Covey called Mr. Nolan to communicate Potlatch concerns over valuation.

On October 2, 2017, the Potlatch board held a special telephonic board meeting. Members of Potlatch management and representatives of BofA Merrill Lynch and Perkins Coie LLP, legal advisor to Potlatch (referred to as “Perkins Coie”) also attended the meeting. At this meeting, Mr. Covey provided an update on his recent discussions with Mr. Nolan, and the Potlatch board discussed the key messages from these recent discussions, including Deltic’s general expectations regarding price. Mr. Covey summarized the strategic rationale for a transaction with Deltic and the proposed terms for a transaction with Deltic. Representatives of BofA Merrill Lynch reviewed its preliminary financial analyses of a potential transaction with Deltic with the Potlatch board and Potlatch management. Perkins Coie reviewed the duties of Potlatch directors under Delaware law. The Potlatch board engaged in discussions regarding the potential transaction, discussing, among other things, the rationale for the transaction, purchase price, synergies, transaction structure and post-closing plans. After further discussion, the Potlatch board authorized management to submit a bid for Deltic at an exchange ratio of 1.8 shares of Potlatch common stock for each share of Deltic common stock and to proceed with negotiations with Deltic on terms consistent with those discussed.

The same day, Potlatch submitted a letter to Deltic setting forth what Potlatch referred to as its final proposal for a transaction between Potlatch and Deltic. The letter outlined a non-binding proposal for a stock-for-stock merger whereby Deltic stockholders would receive 1.8 shares of Potlatch common stock for every share of Deltic common stock. Pursuant to the terms of the offer, Deltic and Potlatch stockholders would own approximately 35% and 65%, respectively, of the combined company. Based on the closing stock price for Potlatch as of the date of the letter, the proposal implied an offer price of $93.15 per share of Deltic common stock. Potlatch noted that Deltic stockholders would benefit from an approximately 5.75x increase in annual dividends, from $0.40 per share to $2.70 per Deltic share after giving effect to the exchange ratio. The letter also proposed that the board of directors of the combined company be comprised of existing board members from both companies, with representation proportional to the respective ownership, meaning that four Deltic representatives would serve on the twelve-person board of the combined company.

On October 5, 2017, the Deltic board held a special meeting at which all of the directors were present, as well as members of Deltic senior management. At the invitation of the Deltic board, representatives of Davis Polk and Goldman Sachs were also in attendance. Davis Polk reviewed with the Deltic board the directors’ fiduciary duties and other legal matters relating to the consideration of a potential strategic transaction. Deltic’s senior management briefed the Deltic board on the status of conversations with Potlatch and estimates of potential synergies. Mr. Enlow and Goldman Sachs also provided the Deltic board with an update on the broader strategic review process. Additionally, Mr. Enlow updated the Deltic board regarding some of the key terms of the stock-for-stock transaction outlined in the most recent Potlatch letter proposal. Goldman Sachs reviewed the financial terms of the transaction proposal by Potlatch, updated the Deltic board on its discussions with Potlatch and representatives of BofA Merrill Lynch and noted that based on their discussions they did not believe Potlatch would be willing to further increase the proposed exchange ratio. Deltic’s senior management also briefed the board regarding Deltic’s standalone plan, including the potential future conversion of the company into a REIT. This review included a discussion of the costs, benefits and risks of the standalone REIT plan, which risks had become more quantifiable since late August. After discussions of the alternatives available to Deltic, the Deltic board concluded that the Potlatch proposal was the best alternative available for maximizing value for the Deltic stockholders. The Deltic board directed management to continue discussions with Potlatch regarding a potential combination of Deltic and Potlatch and instructed Goldman Sachs to indicate to BofA Merrill Lynch that the exchange ratio in Potlatch’s proposal was acceptable and that Deltic was willing to continue discussions on that

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basis but that additional discussions were needed on certain key terms such as corporate governance and executive leadership of the combined company, particularly Mr. Enlow’s role in the management of the combined company, given the significant value of Mr. Enlow’s experience and industry knowledge.

Later that day, representatives of Goldman Sachs advised representatives of BofA Merrill Lynch that the Deltic board had determined that the exchange ratio proposed by Potlatch was acceptable and that Deltic was willing to continue discussions on that basis but that additional discussions were needed on certain key terms such as corporate governance and executive leadership of the combined company. Mr. Covey then updated the Potlatch board.

In the ensuing days, Deltic’s management, Potlatch’s management and their respective advisors engaged in discussions regarding transaction terms, including among other terms, the potential corporate governance structure and executive leadership of the combined company. During this period the parties, including their respective legal and financial advisors, also further progressed in their respective due diligence efforts.

On October 6, 2017, Mr. Nolan called Mr. Covey to further discuss remaining issues relating to board composition, post-merger name, a role for Mr. Enlow and continued presence in El Dorado, Arkansas, and Mr. Covey and Mr. Nolan discussed Mr. Enlow’s role in the combined company.

On October 9, 2017, representatives of Goldman Sachs delivered an initial draft of the merger agreement to representatives of BofA Merrill Lynch. The initial draft of the merger agreement was prepared by Davis Polk. The draft merger agreement provided for a termination fee in certain circumstances, including in the event that either the Deltic board or the Potlatch board changed its recommendation in favor of the potential transaction. The proposed termination fee payable by Potlatch in such circumstances was 5% of the value of Deltic’s outstanding equity, while the proposed termination fee payable by Deltic in such circumstances was 2.5% of the value of Deltic’s outstanding equity.

Following delivery of this draft through October 22, 2017, discussions and negotiations between representatives of Deltic and its advisors, on the one hand, and of Potlatch and its advisors, on the other hand, took place regarding the merger agreement and ancillary documents and the parties exchanged multiple drafts of such documents during this time.

On October 10, 2017, with the consent of the Deltic board, Mr. Enlow met with Mr. Covey in Denver, Colorado to discuss non-financial terms of the transaction including Mr. Enlow’s potential role in the combined company and the terms of such role, board composition of the combined company and executive leadership of the combined company.

On October 11 and 12, 2017, Perkins Coie provided Davis Polk with revised drafts of the merger agreement. The terms of the draft merger agreement included proposed reciprocal termination fees for Potlatch and Deltic equal to 3% of the value of Deltic’s outstanding equity. Davis Polk, Perkins Coie and Skadden held telephone calls to further negotiate the terms of the draft merger agreement and related transaction issues.

On October 15, 2017, Davis Polk provided Perkins Coie with a revised draft of the merger agreement. The draft merger agreement included a proposed termination fee payable by Potlatch equal to 3% of the value of Potlatch’s outstanding equity, and a proposed termination fee payable by Deltic equal to 3% of the value of Deltic’s outstanding equity.

On October 16, 2017, with the consent of the Deltic board, Mr. Enlow spoke with Mr. Covey and reached an agreement regarding Mr. Enlow’s role in the combined company.

On October 17, 2017, Mr. Nolan called Mr. Covey to discuss governance issues and continued presence in El Dorado, Arkansas.

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Between October 17 and October 20, 2017, with the consent of the Deltic board, Mr. Enlow, Mr. Nolan and Mr. Covey discussed open compensation and governance issues.

On October 18, 2017, Potlatch provided representatives of Deltic with a draft of a consulting agreement pursuant to which Mr. Enlow would serve as Vice Chairman of the combined company for a period of two years, during which time Mr. Enlow would assist the Chief Executive Officer of the combined company in the orderly integration of Deltic into Potlatch and advise the Chief Executive Officer and the board of directors of the combined company on strategic issues relating to integration, among other duties. With the consent of the Deltic board, the parties negotiated the terms of Mr. Enlow’s consulting agreement in the ensuing days.

From October 18 through October 22, 2017, Perkins Coie and Davis Polk exchanged comments to the draft merger agreement on a daily basis.

On October 21, 2017, the Deltic board held a special meeting to review the terms of the proposed transaction with Potlatch. At the invitation of the board, representatives from Davis Polk and Goldman Sachs were present. Prior to the meetings, among other things, copies of the draft merger agreement (including the related ancillary documents such as the disclosure letters and governance schedule), presentations prepared by each of Davis Polk and Goldman Sachs and proposed board resolutions were provided to the directors. Davis Polk reviewed with the directors their fiduciary duties with respect to the proposed transaction. Davis Polk also reviewed with the directors the terms of the merger agreement, including the merger consideration provisions, covenants (including the board recommendation and non-solicitation provisions), closing conditions, termination rights and associated termination fees, and governance terms. Representatives of Goldman Sachs confirmed to the Deltic board that Goldman Sachs had not provided any financial advisory or underwriting services to Potlatch for which it had received compensation during the preceding two year period. Goldman Sachs reviewed with the Deltic board its financial analysis of the merger consideration and rendered an oral opinion, confirmed by subsequent delivery of a written opinion, to the Deltic board to the effect that, as of the date of its opinion and based upon and subject to the factors and assumptions set forth in its opinion, the exchange ratio of 1.80 shares of Potlatch common stock to be paid for each outstanding share of Deltic common stock pursuant to the merger agreement was fair from a financial point of view to the holders (other than Potlatch and its affiliates) of Deltic common stock, as more fully described in the section entitled “—Opinion of Deltic’s Financial Advisor” beginning on page 81.

The Deltic board and its advisors discussed Potlatch and the proposed transaction with Potlatch. The Deltic board and its advisors also discussed the standalone options for Deltic, including converting into a REIT, the market conditions and challenges facing Deltic within the industry and the risks of the standalone REIT plan which had become more quantifiable since late August. The Deltic board also discussed the process it had employed, including engaging in discussions with various counterparties, and that given the public disclosure of the process, credible and interested buyers had been given ample opportunity to contact Deltic. The Deltic board considered the benefits of the proposed transaction with Potlatch for the Deltic stockholders and concluded that it was unlikely that any other counterparty would have the strategic interest and financial capability to offer value to Deltic’s stockholders in excess of the proposed transaction with Potlatch. The Deltic board also concluded that the draft merger agreement would not preclude a potential counterparty, if any, from making a potentially superior proposal following the announcement of a transaction with Potlatch. Following its discussions, the board of directors unanimously determined that it was advisable, and in the best interests of, Deltic and its stockholders to enter into the merger agreement, substantially in the form presented, and to consummate the merger and the other transactions contemplated thereby. The directors unanimously authorized and approved the merger agreement, the merger and the other transactions contemplated thereby, directed the merger agreement to be submitted to Deltic’s stockholders for consideration and, subject to the terms of the merger agreement, resolved to recommend that Deltic’s stockholders adopt and approve the merger agreement and the merger.

On October 22, 2017, the Potlatch board held a special meeting. Members of Potlatch management and representatives of BofA Merrill Lynch and Perkins Coie were also in attendance at the meeting. Members of the

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Potlatch board had been provided with a set of meeting materials, including a summary of the terms and conditions of the merger agreement prepared by Perkins Coie, the merger agreement and financial analyses of the proposed transaction prepared by representatives of BofA Merrill Lynch. A representative of Perkins Coie provided an overview of the fiduciary duties applicable to the Potlatch board, as well as an overview of the current state of the merger agreement and various transaction terms. Representatives of BofA Merrill Lynch reviewed disclosures previously provided to the Potlatch board, including information regarding BofA Merrill Lynch’s prior investment banking relationships with Potlatch and Deltic. At this meeting, representatives of BofA Merrill Lynch also reviewed its financial analyses of the proposed transaction. Also at the meeting, representatives of BofA Merrill Lynch rendered an oral opinion to the Potlatch board, confirmed by delivery of a written opinion, dated October 22, 2017, that, as of such date, and based upon and subject to the assumptions made, procedures followed, matters considered and qualifications and limitations set forth in its written opinion, the exchange ratio pursuant to the merger agreement was fair, from a financial point of view, to Potlatch, as more fully described in the section entitled “Opinion of Potlatch’s Financial Advisor” beginning on page 70. Following a discussion of the foregoing matters by members of the Potlatch board, including Potlatch’s other strategic alternatives and prospects as a standalone company, the Potlatch board unanimously (1) approved and adopted the merger agreement, (2) approved the merger upon the terms and subject to the conditions set forth in the merger agreement and (3) approved the issuance by Potlatch of 1.80 shares of Potlatch common stock per share of Deltic common stock pursuant to and in accordance with the terms and conditions of the merger agreement.

Following the October 21, 2017 meeting of the Deltic board, and the October 22, 2017 meeting of the Potlatch board, Deltic and Potlatch executed and delivered the merger agreement on the evening of October 22, 2017. Deltic and Potlatch issued a joint press release announcing the execution of the merger agreement on Monday, October 23, 2017.

Potlatch’s Reasons for the Merger; Recommendation of the Potlatch Board

At its meeting on October 22, 2017, the Potlatch board unanimously (1) approved and adopted the merger agreement, (2) approved the merger upon the terms and subject to the conditions set forth in the merger agreement and (3) approved the issuance by Potlatch of 1.80 shares of Potlatch common stock per share of Deltic common stock pursuant to and in accordance with the terms and conditions of the merger agreement. Accordingly, the Potlatch board unanimously recommends that the Potlatch stockholders vote “FOR” each of the share issuance proposal and the Potlatch adjournment proposal.

In evaluating the merger agreement and the issuance of Potlatch common stock to Deltic stockholders, the Potlatch board consulted with, and received the advice of, Potlatch’s management and its legal and financial advisors. In reaching its decision, the Potlatch board considered a number of factors, including the following factors that the Potlatch board viewed as generally supporting its decision to approve and adopt the merger agreement and recommend that Potlatch stockholders vote “FOR” the share issuance proposal and the Potlatch adjournment proposal.

Strategic Considerations. The Potlatch board believes that the merger will provide a number of significant strategic benefits for Potlatch stockholders, including the following:

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Other Factors Considered by the Potlatch board. In addition to considering the strategic factors described above, the Potlatch board considered the following additional factors, all of which it viewed as supporting its decision:

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The Potlatch board weighed these benefits and supporting factors against a number of other factors identified in its deliberations weighing negatively against the merger, including:

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The Potlatch board considered all of these factors as a whole, and, on balance, concluded that they supported a determination to (1) approve and adopt the merger agreement, (2) approve the merger upon the terms and subject to the conditions set forth in the merger agreement and (3) approve the issuance by Potlatch of 1.80 shares of Potlatch common stock per share of Deltic common stock pursuant to and in accordance with the terms and conditions of the merger agreement. The foregoing discussion of the factors considered by the Potlatch board is not intended to be exhaustive, but rather is a summary of the principal factors considered by the Potlatch board. In light of the number and wide variety of factors considered in connection with its evaluation of the merger and the complexity of these factors, the Potlatch board did not find it useful to, and did not attempt to, quantify, rank or otherwise assign any relative or specific weights to the various factors that it considered in reaching its decision. In considering these factors, individual members of the Potlatch board may have given differing weights to different factors. The Potlatch board conducted an overall review of the factors described above, including thorough discussions with Potlatch’s management and legal and financial advisors.

In considering the recommendation of the Potlatch board to approve the share issuance proposal, Potlatch stockholders should be aware that Potlatch’s directors may have interests in the merger that are different from, or in addition to, those of Potlatch stockholders generally. For additional information, see the section entitled “—Financial Interests of Potlatch Directors and Officers in the Merger” on page 92.

The factors contained in this explanation of the reasoning of the Potlatch board and certain information presented in this section are forward-looking in nature. Therefore, the information should be read in light of the factors discussed in the section entitled “Cautionary Statement Regarding Forward-Looking Statements” beginning on page 26.

Deltic’s Reasons for the Merger; Recommendation of the Deltic Board

The Deltic board has determined that the merger agreement and the transactions contemplated by the merger agreement are advisable and in the best interests of Deltic and its stockholders. Accordingly, by a vote at a meeting held on October 21, 2017, the Deltic board unanimously determined that the merger agreement and the transactions contemplated by the merger agreement were advisable and in the best interests of Deltic and its stockholders and approved the merger agreement and the transactions contemplated by the merger agreement, including the merger.

Accordingly, the Deltic board unanimously recommends that Deltic stockholders vote “FOR” the merger proposal at the Deltic special meeting.

As described in the section entitled “—Background of the Merger” beginning on page 50, the Deltic board consulted with Deltic’s management and Deltic’s legal and financial advisors and, in reaching its determination and recommendation, the Deltic board considered a number of factors.

Many of the factors considered favored the conclusion of the Deltic board that the merger agreement and the transactions contemplated by the merger agreement are advisable and in the best interests of Deltic and its stockholders, including the following (which are not in any relative order of importance):

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In the course of its deliberations, the Deltic board also considered a variety of risks and other potentially negative factors, including the following (which are not in any relative order of importance):

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The Deltic board considered all of these factors as a whole, and, on balance, concluded that they supported a determination to approve the merger agreement and the transactions contemplated by the merger agreement, including the merger. The foregoing discussion of the factors considered by the Deltic board is not intended to be exhaustive, but rather is a summary of the principal factors considered by the Deltic board. In light of the number and wide variety of factors considered in connection with its evaluation of the merger and the complexity of these factors, the Deltic board did not find it useful to, and did not attempt to, quantify, rank or otherwise assign any relative or specific weights to the various factors that it considered in reaching its decision. In considering

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these factors, individual members of the Deltic board may have given differing weights to different factors. The Deltic board conducted an overall review of the factors described above, including thorough discussions with Deltic’s management and legal and financial advisors.

In considering the recommendation of the Deltic board to approve the merger proposal, Deltic stockholders should be aware that Deltic’s directors may have interests in the merger that are different from, or in addition to, those of Deltic stockholders generally. For additional information, see the section entitled “—Financial Interests of Deltic Directors and Officers in the Merger” beginning on page 92.

The factors contained in this explanation of the reasoning of the Deltic board and certain information presented in this section are forward-looking in nature. Therefore, the information should be read in light of the factors discussed in the section entitled “Cautionary Statement Regarding Forward-Looking Statements” beginning on page 26.

Opinion of Potlatch’s Financial Advisor

Potlatch has retained BofA Merrill Lynch to act as Potlatch’s financial advisor in connection with the merger. BofA Merrill Lynch is an internationally recognized investment banking firm, which is regularly engaged in the valuation of businesses and securities in connection with mergers and acquisitions, negotiated underwritings, secondary distributions of listed and unlisted securities, private placements and valuations for corporate and other purposes. Potlatch selected BofA Merrill Lynch to act as Potlatch’s financial advisor in connection with the merger on the basis of BofA Merrill Lynch’s experience in transactions similar to the merger and its reputation in the investment community.

On October 22, 2017, at a meeting of the Potlatch board held to evaluate the merger, BofA Merrill Lynch delivered to the Potlatch board an oral opinion, which was confirmed by delivery of a written opinion dated October 22, 2017, to the effect that, as of the date of the opinion and based on and subject to various assumptions and limitations described in the opinion, the exchange ratio provided for in the merger was fair, from a financial point of view, to Potlatch.

The full text of BofA Merrill Lynch’s written opinion to the Potlatch board, which describes, among other things, the assumptions made, procedures followed, factors considered and limitations on the review undertaken, is attached as Annex B to this document and is incorporated by reference herein in its entirety. The following summary of BofA Merrill Lynch’s opinion is qualified in its entirety by reference to the full text of the opinion. BofA Merrill Lynch delivered its opinion to the Potlatch board for the benefit and use of the Potlatch board (in its capacity as such) in connection with and for purposes of its evaluation of the exchange ratio from a financial point of view. BofA Merrill Lynch’s opinion does not address any other aspect of the merger, and no opinion or view was expressed as to the relative merits of the merger in comparison to other strategies or transactions that might be available to Potlatch or in which Potlatch might engage or as to the underlying business decision of Potlatch to proceed with or effect the merger. BofA Merrill Lynch’s opinion does not constitute a recommendation to any stockholder as to how to vote or act in connection with the proposed merger or any related matter.

In connection with rendering its opinion, BofA Merrill Lynch:

(i) reviewed certain publicly available business and financial information relating to Deltic and Potlatch;

(ii) reviewed certain internal financial and operating information with respect to the business, operations and prospects of Deltic furnished to or discussed with BofA Merrill Lynch by the management of Deltic, including certain financial forecasts relating to Deltic prepared by the management of Deltic, referred to herein as the Deltic Forecasts;

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(iii) reviewed certain financial forecasts relating to Deltic prior to tax savings and certain tax savings forecasts relating to Deltic, in each case prepared by the management of Potlatch, referred to herein as the Potlatch-Deltic Including Tax Savings Forecasts, and discussed with the management of Potlatch its assessments as to the relative likelihood of achieving the future financial results reflected in the Deltic Forecasts and the Potlatch-Deltic Including Tax Savings Forecasts;

(iv) reviewed certain internal financial and operating information with respect to the business, operations and prospects of Potlatch furnished to or discussed with BofA Merrill Lynch by the management of Potlatch, including certain financial forecasts relating to Potlatch prepared by the management of Potlatch, referred to herein as the Potlatch Forecasts;

(v) reviewed certain estimates as to the amount and timing of cost synergies anticipated by the management of Potlatch to result from the merger, referred to herein as the Cost Synergies;

(vi) discussed the past and current business, operations, financial condition and prospects of Deltic with members of senior managements of Deltic and Potlatch, and discussed the past and current business, operations, financial condition and prospects of Potlatch with members of senior management of Potlatch;

(vii) reviewed the potential pro forma financial impact of the merger on the future financial performance of Potlatch, including the potential effect on Potlatch’s estimated cash available for distribution, and the relative financial contributions of Deltic and Potlatch to the future financial performance of the combined company on a pro forma basis;

(viii) reviewed the trading histories for Deltic common stock and the Potlatch common stock and a comparison of such trading histories with each other and with the trading histories of other companies BofA Merrill Lynch deemed relevant;

(ix) compared certain financial and stock market information of Deltic and Potlatch with similar information of other companies BofA Merrill Lynch deemed relevant;

(x) reviewed the merger agreement; and

(xi) performed such other analyses and studies and considered such other information and factors as BofA Merrill Lynch deemed appropriate.

In arriving at its opinion, BofA Merrill Lynch assumed and relied upon, without independent verification, the accuracy and completeness of the financial and other information and data publicly available or provided to or otherwise reviewed by or discussed with it and relied upon the assurances of the managements of Potlatch and Deltic that they were not aware of any facts or circumstances that would make such information or data inaccurate or misleading in any material respect.

With respect to the Deltic Forecasts, BofA Merrill Lynch was advised by Deltic, and assumed, that they were reasonably prepared on bases reflecting the best currently available estimates and good faith judgments of the management of Deltic as to the future financial performance of Deltic. With respect to the Potlatch-Deltic Including Tax Savings Forecasts, the Potlatch Forecasts and the Cost Synergies, BofA Merrill Lynch assumed, at the direction of Potlatch, that they were reasonably prepared on bases reflecting the best currently available estimates and good faith judgments of the management of Potlatch as to the future financial performance of Deltic and Potlatch and the other matters covered thereby and, based on the assessments of the management of Potlatch as to the relative likelihood of achieving the future financial results reflected in the Deltic Forecasts and the Potlatch-Deltic Including Tax Savings Forecasts, BofA Merrill Lynch relied, at the direction of Potlatch, on the Potlatch-Deltic Including Tax Savings Forecasts for purposes of its opinion. BofA Merrill Lynch also relied, at the direction of Potlatch, on the assessments of the management of Potlatch as to Deltic’s ability to achieve the

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tax savings forecasts relating to Deltic included in the Potlatch-Deltic Including Tax Savings Forecasts and Potlatch’s ability to achieve the Cost Synergies and was advised by Potlatch, and assumed, that the tax savings forecasts relating to Deltic included in the Potlatch-Deltic Including Tax Savings Forecasts and the Cost Synergies would be realized in the amounts and at the times projected.

BofA Merrill Lynch did not make, and was not provided with, any independent evaluation or appraisal of the assets or liabilities (contingent or otherwise) of Deltic or Potlatch, nor did it make any physical inspection of the properties or assets of Deltic or Potlatch. BofA Merrill Lynch did not evaluate the solvency or fair value of Deltic or Potlatch under any state, federal or other laws relating to bankruptcy, insolvency or similar matters. BofA Merrill Lynch assumed, at the direction of Potlatch, that the merger would be consummated in accordance with its terms, without waiver, modification or amendment of any material term, condition or agreement and that, in the course of obtaining the necessary governmental, regulatory and other approvals, consents, releases and waivers for the merger, no delay, limitation, restriction or condition, including any divestiture requirements or amendments or modifications, would be imposed that would have an adverse effect on Deltic, Potlatch or the contemplated benefits of the merger. BofA Merrill Lynch also assumed, at the direction of Potlatch, that the merger would qualify for federal income tax purposes as a reorganization under the provisions of Section 368(a) of the Internal Revenue Code of 1986, as amended.

BofA Merrill Lynch expressed no view or opinion as to any terms or other aspects of the merger (other than the exchange ratio to the extent expressly specified in its opinion), including, without limitation, the form or structure of the merger. BofA Merrill Lynch’s opinion was limited to the fairness, from a financial point of view, to Potlatch of the exchange ratio provided for in the merger and no opinion or view was expressed with respect to any consideration received in connection with the merger by the holders of any class of securities, creditors or other constituencies of any party. In addition, no opinion or view was expressed with respect to the fairness (financial or otherwise) of the amount, nature or any other aspect of any compensation to any of the officers, directors or employees of any party to the merger, or class of such persons, relative to the exchange ratio. Furthermore, no opinion or view was expressed as to the relative merits of the merger in comparison to other strategies or transactions that might have been available to Potlatch or in which Potlatch might have engaged or as to the underlying business decision of Potlatch to proceed with or effect the merger. BofA Merrill Lynch did not express any opinion as to what the value of the Potlatch common stock actually would be when issued or the prices at which Potlatch common stock or Deltic common stock will trade at any time, including following announcement or consummation of the merger. In addition, BofA Merrill Lynch expressed no opinion or recommendation as to how any stockholder should vote or act in connection with the merger or any related matter.

BofA Merrill Lynch’s opinion was necessarily based on financial, economic, monetary, market and other conditions and circumstances as in effect on, and the information made available to BofA Merrill Lynch as of, the date of its opinion. It should be understood that subsequent developments may affect its opinion, and BofA Merrill Lynch does not have any obligation to update, revise or reaffirm its opinion. The issuance of BofA Merrill Lynch’s opinion was approved by a fairness opinion review committee of BofA Merrill Lynch.

The discussion set forth below in the sections entitled “Selected Publicly Traded Companies Sum-of-the-Parts Analysis”, “Hybrid NAV Sum-of-the-Parts Analysis”, “Discounted Cash Flow Sum-of-the-Parts Analysis”, “Financial Analysis of Combination” and “Contribution Analysis” represents a brief summary of the material financial analyses presented by BofA Merrill Lynch to Potlatch’s board in connection with its opinion. The financial analyses summarized below include information presented in tabular format. In order to fully understand the financial analyses performed by BofA Merrill Lynch, the tables must be read together with the text of each summary. The tables alone do not constitute a complete description of the financial analyses performed by BofA Merrill Lynch. Considering the data set forth in the tables below without considering the full narrative description of the financial analyses, including the methodologies and assumptions underlying the analyses, could create a misleading or incomplete view of the financial analyses performed by BofA Merrill Lynch.

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Selected Publicly Traded Companies Sum-of-the-Parts Analysis

BofA Merrill Lynch reviewed publicly available financial and stock market information for the following three publicly traded companies in the timber REIT sector and the following five publicly traded companies in the wood product sector:

Timber REIT Sector

Weyerhaeuser Company;

Rayonier Inc.; and

CatchMark Timber Trust Inc.

Wood Product Sector

Louisiana-Pacific Corporation;

West Fraser Timber Co., Ltd.;

Norbord Inc.;

Canfor Corporation; and

Boise Cascade Company.

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BofA Merrill Lynch reviewed, among other things, adjusted enterprise values of the selected publicly traded companies in the timber REIT and wood product sectors, calculated as equity values based on closing stock prices on October 20, 2017, plus debt, unfunded pension liabilities (after-tax), preferred equity and minority interests, less cash and marketable securities, as a multiple of calendar year 2018 estimated adjusted earnings before interest, taxes, depreciation, depletion and amortization, commonly referred to as adjusted EBITDDA. BofA Merrill Lynch then applied (i) a range of adjusted enterprise value to adjusted EBITDDA multiples of 16.0x to 18.0x, based on valuation ranges for the selected publicly traded companies in the timber REIT sector, to the calendar year 2018 estimated adjusted EBITDDA for Potlatch’s Resource / Woodlands and Real Estate segments, (ii) a range of adjusted enterprise value to adjusted EBITDDA multiples of 6.0x to 7.0x, based on valuation ranges for the selected publicly traded companies in the wood product sector, to the calendar year 2018 estimated adjusted EBITDDA for Potlatch’s Wood Products / Manufacturing segment and (iii) a range of adjusted enterprise value to adjusted EBITDDA multiples of 12.9x to 14.5x, based on the valuation ranges for the Resource / Woodlands and Real Estate and the Wood Products / Manufacturing segments blended based on respective EBITDDAs, to the calendar year 2018 estimated adjusted EBITDDA for Potlatch’s Corporate segment (adjusted to add back pension expenses). BofA Merrill Lynch also applied (i) a range of adjusted enterprise value to adjusted EBITDDA multiples of 16.0x to 18.0x, based on valuation ranges for the selected publicly traded companies in the timber REIT sector, to the calendar year 2018 estimated adjusted EBITDDA for Deltic’s Resource / Woodlands and Real Estate segment, (ii) a range of adjusted enterprise value to adjusted EBITDDA multiples of 6.0x to 7.0x, based on valuation ranges for the selected publicly traded companies in the wood product sector, to the calendar year 2018 estimated adjusted EBITDDA for Deltic’s Wood Products / Manufacturing segment and (iii) a range of adjusted enterprise value to adjusted EBITDDA multiples of 11.0x to 12.5x, based on the valuation ranges for the Resource / Woodlands and Real Estate and the Wood Products / Manufacturing segments blended based on respective EBITDDAs, to the calendar year 2018 estimated adjusted EBITDDA for Deltic’s Corporate segment (adjusted to add back pension expenses). Estimated financial data of Potlatch were based on the Potlatch Forecasts, and estimated financial data of Deltic were based on the Potlatch-Deltic Including Tax Savings Forecasts. After accounting for debt and after-tax unfunded pension liabilities, these analyses indicated the following approximate implied per share equity value reference ranges for Potlatch, as compared to its share price of $53.00 as of October 20, 2017, and Deltic, as compared to its share price of $89.12, as of October 20, 2017:

Implied Per Share Equity Value Sum-of-the-Parts Reference Ranges for Potlatch

(Based on Potlatch Forecasts and Information per Potlatch Management)

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Implied Per Share Equity Value Sum-of-the-Parts Reference Ranges for Deltic

(Based on Potlatch-Deltic Including Tax Savings Forecasts and Deltic filings)

No company used in these analyses is identical or directly comparable to Potlatch or Deltic. Accordingly, an evaluation of the results of the analyses is not entirely mathematical. Rather, the analyses involve complex considerations and judgments concerning differences in financial and operating characteristics and other factors that could affect the public trading or other values of the companies to which Potlatch and Deltic were compared.

Hybrid NAV Sum-of-the-Parts Analysis

Based on the Potlatch Forecasts and publicly available financial and stock market information, BofA Merrill Lynch reviewed a range of timberland resource values for properties owned or leased on a long-term basis by Potlatch as well as a range of incremental highest and best use real estate values, referred to as incremental HBU, above the timberland resource values for such properties to derive a range of Total Resource / Woodlands and Real Estate Values. BofA Merrill Lynch then applied a range of adjusted enterprise value to adjusted EBITDDA multiples of 6.0x to 7.0x, based on valuation ranges for the selected publicly traded companies in wood products sector, to Potlatch’s calendar year 2018 estimated adjusted EBITDDA attributable to its Wood Products / Manufacturing segment. BofA Merrill Lynch then combined the range of Total Resource / Woodlands and Real Estate Values with the range of total enterprise values attributable to its Wood Products / Manufacturing segment to produce a range of total enterprise values for Potlatch. After accounting for debt and after-tax unfunded pension liabilities, this analysis indicated the following approximate implied per share equity value reference range for Potlatch as compared to its share price of $53.00 as of October 20, 2017:

Implied Per Share Equity Value Reference Ranges for Potlatch

(Based on Potlatch Forecasts, Information per Potlatch Management and analyst estimates)

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Based on the Potlatch-Deltic Including Tax Savings Forecasts and publicly available financial and stock market information, BofA Merrill Lynch reviewed a range of timberland resource values for properties owned by Deltic as well as a range of incremental HBU values above the timberland resource values for such properties in addition to real estate values, including values of developed residential lots, undeveloped residential lots and remaining commercial acres, of properties held by Deltic to derive a range of Consolidated Resource / Woodlands and Real Estate Values. BofA Merrill Lynch then applied a range of adjusted enterprise value to adjusted EBITDDA multiples of 6.0x to 7.0x, based on valuation ranges for the selected publicly traded companies in the wood products sector, to Deltic’s calendar year 2018 estimated adjusted EBITDDA attributable to its Wood Products / Manufacturing segment. BofA Merrill Lynch then combined the range of Combined Resource / Woodlands and Real Estate Values with the range of total enterprise values attributable to its Wood Products / Manufacturing segment to produce a range of total enterprise values for Deltic. After accounting for debt and after-tax unfunded pension liabilities, this analysis indicated the following approximate implied per share equity value reference range for Deltic as compared to its share price of $89.12 as of October 20, 2017:

Implied Per Share Equity Value Reference Ranges for Deltic

(Based on Potlatch-Deltic Including Tax Savings Forecasts, Deltic filings and analyst estimates)

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Discounted Cash Flow Sum-of-the-Parts Analysis

BofA Merrill Lynch performed a discounted cash flow sum-of-the-parts analysis of Potlatch to calculate the present value of the standalone unlevered, after-tax free cash flows that Potlatch’s business segments were forecasted to generate during the last quarter of 2017 through calendar year 2021 based on the Potlatch Forecasts and publicly available financial and stock market information. BofA Merrill Lynch also calculated terminal values for each Potlatch business segment by applying (i) a range of perpetuity growth rates of (a) 1.50% to 2.00% for Potlatch’s Resource / Woodlands and Real Estate segment and (b) 1.50% to 2.50% for Potlatch’s Wood Products / Manufacturing and Corporate segments to the respective Potlatch business segments’ estimated calendar year 2021 free cash flows (adjusted to account for capital expenditures, depreciation, depletion and amortization) and (ii) a range of discount rates of (a) 6.75% to 8.00% for Potlatch’s Woodlands segment, (b) 6.50% to 7.50% for Potlatch’s Real Estate segment, (c) 11.00% to 13.50% for Potlatch’s Wood Products / Manufacturing segment and (d) 8.00% to 10.00% for Potlatch’s Corporate segment, all of which were based on an estimate of each Potlatch business segment’s respective weighted average cost of capital. The free cash flows and terminal values for each business segment were discounted to present value as of September 30, 2017 using discount rates ranging from (i) 6.75% to 8.00% for Potlatch’s Woodlands segment, (ii) 6.50% to 7.50% for Potlatch’s Real Estate segment, (iii) 11.00% to 13.50% for Potlatch’s Wood Products / Manufacturing segment and (iv) 8.00% to 10.00% for Potlatch’s Corporate segment (adjusted to add back Potlatch’s pension expenses of $1.6 million in the last quarter of 2017, $5.9 million in calendar year 2018, $3.9 million in calendar year 2019, $10.2 million in calendar year 2020, and $7.7 million in calendar year 2021), all of which were based on an estimate of each Potlatch business segment’s weighted average cost of capital. The range of Potlatch’s implied total equity values was then calculated by (i) combining each of the low enterprise values of Potlatch’s four business segments and (ii) combining each of the high enterprise values of Potlatch’s four business segments, in each case, less net debt (which includes Potlatch’s unfunded pension liability of $72 million). This analysis indicated the following approximate implied per share equity value reference range for Potlatch, rounded to the nearest $0.05, as compared to its share price of $53.00 as of October 20, 2017:

Discounted Cash Flow – Sum-of-the-Parts Analysis for Potlatch

(Based on Potlatch Forecasts and Potlatch filings)

BofA Merrill Lynch performed a discounted cash flow sum-of-the-parts analysis of Deltic to calculate the present value of the standalone unlevered, after-tax free cash flows that Deltic’s business segments were forecasted to generate during the last quarter of 2017 through calendar year 2021 based on the Potlatch-Deltic Including Tax Savings Forecasts and publicly available financial and stock market information. BofA Merrill Lynch also calculated terminal values for Deltic’s business segments by applying (i) a range of perpetuity growth rates of (a) 2.50% to 3.00% for Deltic’s Resource / Woodlands and Real Estate segment and (b) 1.50% to 2.50% for Deltic’s Wood Products / Manufacturing and Corporate segments to the respective Deltic business segments’ estimated calendar year 2021 free cash flows (adjusted to account for capital expenditures, depreciation, depletion and amortization) and (ii) a range of discount rates of (a) 6.50% to 7.50% for Deltic’s Resource / Woodlands and Real Estate segment, (b) 11.00% to 13.50% for Deltic’s Wood Products / Manufacturing segment and (c) 8.25% to 10.00% for Deltic’s Corporate segment (adjusted to add back Deltic’s pension

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expenses of $1.5 million), all of which were based on an estimate of each Deltic business segment’s respective weighted average cost of capital. The free cash flows and terminal values for each business segment were then discounted to present value as of September 30, 2017 using discount rates ranging from (i) 6.50% to 7.50% for Deltic’s woodlands and real estate segments, (ii) 11.00% to 13.50% for Deltic’s wood products and manufacturing segment and (iii) 8.25% to 10.00% for Deltic’s Corporate segment, all of which were based on an estimate of each Deltic business segment’s respective weighted average cost of capital. At the direction of Potlatch’s management, BofA Merrill Lynch assumed a corporate tax savings to Deltic’s Resource / Woodlands and Real Estate segment due to a REIT conversion. Based on the projected tax savings included in the Potlatch-Deltic Including Tax Savings Forecasts, BofA Merrill Lynch calculated the present value of the estimated tax savings during the last quarter of 2017 through calendar year 2021. BofA Merrill Lynch also calculated the terminal values of Deltic’s estimated tax savings by applying a range of perpetuity growth rates of 1.5% to 2.5% to Deltic’s calendar year 2021 estimated tax savings and a range of discount rates of 6.50% to 7.50%, which were based on an estimate of the weighted average cost of capital of Deltic’s Resource / Woodlands and Real Estate business segment. BofA Merrill Lynch discounted Deltic’s estimated tax savings and the terminal values of Deltic’s estimated tax savings to present value as of September 30, 2017 using discount rates ranging from 6.50% to 7.50%, which were based on based on an estimate of the weighted average cost of capital of Deltic’s Resource / Woodlands and Real Estate business segment. In deriving an implied per share equity value reference range for Deltic, BofA Merrill Lynch considered scenarios including and excluding the Cost Synergies. For the scenario including the Cost Synergies, BofA Merrill Lynch calculated the present value of the estimated the Cost Synergies during the last quarter of 2017 through calendar year 2021, based on the Potlatch-Deltic Including Tax Savings Forecasts. BofA Merrill Lynch also calculated the terminal values of the Cost Synergies by applying a range of perpetuity growth rates of 1.5% to 2.5% to Deltic’s calendar year 2021 estimated Cost Synergies and a range of discount rates of 8.25% to 10.00%, which were based on an estimate of Deltic’s weighted average cost of capital. BofA Merrill Lynch discounted the Cost Synergies and terminal values of the Cost Synergies to a present value as of September 30, 2017 using discount rates ranging from 8.25% to 10.00%, which were based on an estimate of Deltic’s weighted average cost of capital. The range of Deltic’s implied total equity values was then calculated by combining each of the enterprise values of Deltic’s four business segments, the total value of Deltic’s estimated tax savings and, in the scenario including the Cost Synergies, the total value of the Cost Synergies, less net debt (which includes Deltic’s unfunded pension liability of $24 million). This analysis indicated the following approximate implied per share equity value reference ranges for Deltic, rounded to the nearest $0.05, as compared to its share price of $89.12 as of October 20, 2017:

Discounted Cash Flow – Sum-of-the-Parts Analysis for Deltic

(Based on Potlatch-Deltic Including Tax Savings Forecasts, Potlatch filings and Potlatch management’s projections for the Cost Synergies)

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Financial Analysis of Combination

Based on implied equity value reference ranges for Potlatch and Deltic calculated as described above in the sections entitled “Selected Publicly Traded Companies Sum-of-the-Parts Analysis”, “Hybrid NAV Sum-of-the-Parts Analysis” and “Discounted Cash Flow Sum-of-the-Parts Analysis”, BofA Merrill Lynch calculated implied exchange ratios resulting from one share of Deltic being converted into shares of Potlatch, with the top of the range based on the highest Deltic implied equity value and the lowest Potlatch implied equity value and the bottom of the range based on the lowest Deltic implied equity value and the highest Potlatch implied equity value. These analyses indicated the following implied exchange ratio reference ranges, in each case as compared to the exchange ratio of 1.800:

Implied Exchange Ratio reference ranges based on: