Prevalence, epidemiology and management of potato late blight in Bangladesh

Late blight (Phytophthora infestans) is the most potential disease threat to the potato production in Bangladesh. epidemiological studies indicate that the disease appears in the first week of January when the day temperature range 14–19°c and night temperature 9–14°c accompanied with foggy weather and heavy deposition of dew drops. The sporangial production accelerated when temperature gradient ranged 15–20°c and low temperature (10–13°c) supports enormous production of zoospore. Twenty races of P. infestans have been identified in the country. initially simple races were predominant but in last five years complex races have recorded. The complex races are predominant in the northern part of the country where winter sets earlier and continues for longer period. Twelve cip clones were tested for late blight resistance at three locations in 2006–07 and 2007–08. cip-393077.159 had moderate resistance to late blight under all three locations. some of the clones yielded over 40t/ha but were highly susceptible to late blight. The indiscriminate use of metalaxyl containing fungicides throughout the country has developed metalaxyl resistant strain of P. infestans. Till now more than 30 fungicides such as mancozeb, phenylamides copper, dimethomorph, chlorothalonil, phenomadone, priopaneb have been registered in the country. The varieties raja, dheera.