Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 7/15/2006
Publication Date: 7/15/2006
Citation: Tooley, P.W., Browning, M.E., Englander, L. 2006. Recovery of phytophthora ramorum following exposure to temperature extremes. Phytopathology 96:S115
Technical Abstract: The temperature limitations on establishment of Phytophthora ramorum (isolate Pr-52) in regions outside of the Pacific northwest are still unknown. To identify temperatures and exposure periods lethal to P. ramorum, we exposed hyphal colonies to temperatures ranging from -5 to -25 deg C for up to 24 hr, and from 30 to 50 deg C for up to 8 hr. In addition, infected Rhododendron Cunningham’s White leaves (0.3 cm2) were incubated in sand, sandy loam, and loam moistened to 30% or 60% water-holding-capacity for up to 7 days. Survival was characterized by recovery of P. ramorum on V8 or PARPH selective media. Hyphal colonies failed to regrow following incubation at temperatures of 42.5 deg C for under 10 min, 40 deg C for 15 min, and 37.5 deg C for 2 hr. There was still some recovery of colonies following 24 hr incubation at -25 deg C, the lowest temperature tested. There was no recovery of P. ramorum from infected leaf disks, irregardless of media or moisture levels, following incubation at 40 deg C for 3 days, 35 deg C for 4 days, or -20 deg C for 2 to 4 days. Longterm studies employing diurnal temperatures based on historical weather data are in progress.