Temperature Tolerance and Survival of Ceratocystis fagacearum in Texas. R. Lewis, Jr., Research Plant Pathologist, Southern Hardwoods Laboratory, U.S. Forest Service, Stoneville, MS 38776. Plant Dis. 69:443-444. Accepted for publication 1 December 1984. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1985. DOI: 10.1094/PD-69-443.

Isolates of Ceratocystis fagacearum from Texas and North Carolina grew most rapidly at 22–26 C and survived without growth for 10 days at 34 C. Some isolates survived for 3 hr at 45 C, but all were dead after 4, 24, and 48 hr, respectively, at 45, 42, and 37 C. Sapwood temperatures of Quercus virginiana, healthy and affected by oak wilt, were compared with ambient temperature for 2 days in July in Kerrville, TX. During the hottest part of the day, sapwood temperatures were lower in healthy than in diseased trees and root collar temperatures were lower than those of the trunk at 1.4-m height or of ambient air. Sapwood temperatures in the root collar of a healthy tree remained at 24.5 C when ambient temperature surpassed 36 C. Air temperatures in Texas in summer permit survival of C. fagacearum, and sapwood temperatures in the lower trunk and roots of healthy trees permit its growth.