Impact of Sowing Environment and Weather Parameters on Progression of Alternaria Blight Disease of Mustard

Alternaria blight disease of mustard caused by Alternaria brassicae (Berk.)Sacc., is an economically destructive disease of mustard.In the present investigation, a field experiment was conducted to know the effect of date of sowing and weather parameters on alternaria blight disease severity progression.The twenty eight genotypes of mustard were sown on three different dates i.e., 22nd October (Early), 13 th November (Mid) and 3 rd December (Late).A progressive increase in Alternaria blight disease severity, apparent infection rate and area under disease progress curve (AUDPC) were observed on both leaves and siliqua in almost all the genotypes irrespective of sowing conditions.Maximum infection was recorded in 3 rd December followed by 13 th November and least infection was recorded in 22 nd October planting.Maximum yield was recorded in genotypes sown on 22 nd October whereas minimum yield was recorded in 3 rd December sowing.A correlation was also established between disease severity and weather parameter to comprehend the influence of weather parameters on disease development.The correlation analysis exhibited a positive correlation between disease severity with maximum and minimum temperature and negative correlation with maximum and minimum relative humidity for mid and late sown conditions while negative correlation with maximum temperature, positive correlation with minimum temperature as well as maximum and minimum relative humidity.The early sown mustard crops could escape severe infection of alternaria blight disease due to susceptible stage of host surpass before the alternaria blight epidemic and increase the yield of the mustard.