NEW YORK, Feb. 14, 2018 /PRNewswire/ — Seacoast Banking Corporation of Florida (NASD: SBCF) will replace Deltic Timber Corp. (NYSE:DEL) in the S&P SmallCap 600 effective prior to the open of trading on Wednesday, February 21. S&P MidCap 400 constituent Potlatch Corp. (NASD:PCH)…