Impacts of Integrated Nutrient Management on Epidemiology, Seed Yield and Severity of Alternaria blight Disease in Indian Mustard (Brassica juncea L.)

The field studies were conducted at the research farm, Bidhan Chandra Krishi Viswavidyalaya, Nadia, West Bengal, India during rabi seasons of 2017–18 and 2018–19. The objective of the research was to establish a relationship between disease severity of Alternaria blight with epidemiological factors in Indian mustard under Integrated Nutrient Management. Severity of disease in the specified time intervals was measured under 10 different nutrient management treatments combinations. Results showed that the highest intensity of Alternaria blight was observed with a mean maximum temperature of 19.3 to 24.4°C, mean minimum temperature of 7.6 to 14.1°C, average temperature of 13.5 to 19.3°C and an average relative humidity of more than 70%. The nutrient management in different combinations resulted different disease severity on leaves and pods and with increase in the age of the plant, significant increase in disease severity was observed. Maximum increase in disease severity was observed on 95 days after sowing (DAS) (44.77%) followed by 80 DAS (38.99%) and 65 DAS (32.99%) irrespective of their different treatments. Minimum disease severity was observed (13.83%) when the plots were treated with Azotobacter @ 250 g kg-1 seed, Phosphobacteria @ 250 g kg-1 seed along with FYM @ 7.5 t ha-1. Empirical relationship was established between different weather factors and Alternaria blight under different nutrient management practices which will be useful to forecast the first appearance of the disease accurately.