Epidemiology of black fruit spot (Alternaria alternata) disease of ber in Punjab: An agrometeorological approach

The periodical development of ber black fruit spot (Alternaria alternata) disease in relation to prevailing weather parameters was investigated at Punjab Agricultural University, Ludhiana during 2018 and 2019 on ber cultivar Sanuar-2. The disease initiated during the 4^th agrometeorological week of January and showed continuous increasing trend till 13^th agrometeorological week in March. The maximum disease incidence was noticed in March (11^th–13^th agrometeorological week) and lowest in January (3^rd–4^th agrometeorological week). In general, 15–25°C temperature, 5–10 sunshine hours, 51–74 per cent relative humidity and 5.7–18.9 mm rainfall were found more favorable for disease development. The temperature >15°C was more favorable where as <10°C was unconducive for disease development. The disease showed highly significant positive correlation with temperature and sunshine and significant negative correlation with relative humidity and rainfall. A forecasting model was also computed for prediction of disease. The expected disease was closely associated with the observed disease incidence.