Effect of weather parameters on the development of Alternaria blight of fennel incited by Alternaria alternata (Fr.) Keissler

Abstract

Diseases and pests are the important constraint in the production of fennel. An experiment was conducted at the Agronomy Farm, S.K.N. College of Agriculture, Jobner during rabi 2013-14 and 2014-15 to investigate the role of weather conditions like humidity, temperature, rainfall and sunshine on this diseases development. The first visible symptoms of disease first appeared during first week of February, became conspicuous from second week of February to second week of March and declined by the third week of March. The maximum development of Alternaria blight was favoured by a mean temperature ranging between 10.6 to 27.8°C and 10 to 27.1 °C along with an average relative humidity 58.5% and 51.5% of more than 70% during during rabi 2013-14 and 2014-15 respectively. The results of two consecutive cropping seasons with respect to weather parameters revealed that Alternaria blight of fennel is greatly favoured by relative humidity more than 80% and rainfall. A significant and positive correlation was recorded with morning and evening relative humidity whereas a negative non-significant correlation with maximum and minimum temperature during 2013-14 while negative significant correlation was obtained with maximum and minimum temperature during 2014-15.