Epidemiological study of Alternaria blight of cabbage in Jorhat district of Assam, India

The field experiment conducted during the period of 2021-2022 at the Department of Horticulture, AAU, Jorhat, has shown that the timing of transplantation significantly impacts the severity of Alternaria blight in cabbage. The study revealed that the timing of transplanting significantly affects disease severity. The crop transplanted in the month of December exhibited the highest disease intensity (maximum and minimum temperatures 24.76°C and 10.58°C, morning and evening relative humidity 98.41% and 57.13% respectively). The disease intensity was the lowest in October transplanted crops (maximum and minimum temperature 26.94°C and 12.22°C, relative humidity morning 96.12% and evening 55.13% respectively). The December transplanted crop had the highest AUDPC at 1317.75, followed by the February transplanted crop at 1037.85. With respect to the correlation matrix, rainfall and relative humidity showed a strong positive correlation with PDI whereas BSSH and temperature (maximum and minimum) all revealed a negative correlation. The multiple regression analysis revealed a substantial relation between disease intensity and meteorological conditions. The multiple regression equation indicated that the overall influence of all environmental parameters, namely (maximum and minimum) temperature, (morning and evening) relative humidity, rainfall, and BSSH on disease development ranged from 63.19% to 82.94%.