Influence of weather parameters on the development of ber black fruit spot (Alternaria alternata) disease on cultivar Umran

Ber black fruit spot (Alternaria alternata) disease development in relation to agrometeorological parameters was studied at PaU, Ludhiana during the period from 2018 and 2019 on cultivar Umran. the disease appeared during 4^th agrometeorological week and showed continuous increasing trend till 13^th agrometeorological week. the maximum disease incidence was noticed during the month of March and lowest in the month of january. In general, 15–25°C temperature, 5–10 sunshine hours/day, 51–74% RH and 5.7–18.9 mm rainfall were more favorable for disease development on the ber fruit. The temperature >17°C was more favorable for the disease progression where as <10°C was unconducive for disease development. The disease showed positive correlation with temperature and sunshine, and negative correlation with relative humidity and rainfall. a prediction model for forecasting the disease with prevailing agro-meteorological parameters was computed for devising a judicious spray schedule. the expected disease was closely associated with observed disease incidence.