Effects of temperature and leaf wetness on the potato late blight

Abstract

The time required for potato late blight lesions, caused by Phytophthora infestans (Mont.) de Bary, to produce sporangia during periods of continuous leaf wetness, and for inoculations to produce lesions bearing sporangia, was determined over a temperature range of 5-24°C. Equations were derived relating time to sporulate with temperature. A 2-h break in leaf wetness, initiated at any time within the first 3 h of incubation after inoculation, markedly reduced lesion numbers. When the break was initiated later it had less effect, except at the lowest temperature tested (9°C). © Crown 1990.