VIEW ARTICLE

Ecology and Epidemiology

Effect of Soil Temperature on the Field Infection of Potato Tubers by Phytophthora infestans. Norio Sato, Plant pathologist, Hokkaido National Agricultural Experiment Station, Hitsujigaoka-1, Sapporo, Japan; Phytopathology 69:989-993. Accepted for publication 8 February 1979. Copyright 1979 The American Phytopathological Society. DOI: 10.1094/Phyto-69-989.

Weather data were analyzed to determine conditions that favor field infection of potato tubers by P. infestans in soil. Soil temperature during and immediately after rain affected the frequency of tuber rot more than did the amount of rain. Tuber infection was high in wet, cool soil but low in wet, warm soil. Tuber infection was markedly decreased in soils with temperatures above 18 C. Cool water (below 17 C) favored indirect germination of sporangia and prolonged the swimming of zoospores but warm water (above 20 C) did not. Tuber infection depended on the release and motility of zoospores. A soil temperature of 18 C or below appeared to be necessary for tuber infection.