Correlation between humid thermal ratio and epidemics of cercospora leaf spot of peanut in pothwar

The epidemic of cercospora leaf spot (cls) frequently led to yield losses on unsprayed peanuts in pakistan. during 3 successive years of field trials under medium rainfall conditions of pothwar at chakwal,it was observed that cls incidence epidemic differed significantly during crop seasons. genotypes exhibited significantly different disease response to cls incidence provided suitable environmental conditions prevailed during crop growth cycle. among crop seasons,year 2003 was most conducive due to frequent and early rains making humid thermal ratio (htr) quite favorable for most of the time for disease initiation and development resulting in higher values of audpcs and incidence. six fortnights from july to september were the most critical and risky for crop as the htr values 2.01 to 3.84 are most likely conducive for significant increase in cls incidence.