Ecological studies and prediction of the onset of potato late blight under egyptian climatic conditions

Abstract

Severe epidemics of late blight have emerged in both 2000 and 2001 in Egypt, making potato production particularly challenging. An indicator variable for the occurrence of blight outbreak during the season is based on the number of favorable days in terms of temperature and relative humidity. Favorable days during November to January were used to describe the disease status throughout the tested period. Statistical modeling of late blight progress data was studied. The disease progress curves, disease rates and the area under disease progress curve (AUDPC) were estimated. Mild and warm nights allow the disease become established on early cultivars. This build-up of inoculums early in the year leads to a tendency for blight to appear in later-planted potato crops. Wet warm winter seasons were important factors influencing development of the recent late blight epidemics in Egypt. Late blight was expected to appear within 7-10 days after the occurrence of ten consecutive disease severity values.