In the present context, cotton farming in India is far from being a sustainable agricultural system. India is the second-largest producer of conventional cotton after China. More than 90% of the cotton is produced from genetically modified, pest-resistant, high yielding Bt cotton varieties. In relation to weather parameters, impact of different meteorological parameters on development of leaf blight on cotton, first leaf blight (Alternaria macrospora) symptoms were appeared on 37th and 39th standard meteorological week during 2020-21 and 2021-22, respectively. In correlation study, maximum temperature was non-significant with negative effect on leaf blight disease development in year 2020-21, while maximum temperature was also non-significant but positive effect leaf blight disease development in year 2021-22. Minimum temperature was non-significant with negative effect in year 2020-21 and 2021-22, respectively. Morning and evening relative humidity was significant and highly significant in both years, respectively and wind speed opposite to RH. Regression study, in year 2020-21 reflect that one per cent increase in morning relative humidity and wind speed led to corresponding decrease in per cent disease index of Alternaria blight in 2020-21 and 2021-22. This study focuses on impact of weather parameters on fungal foliar diseases and tackles the problem as well. Weather parameters play vital and crucial role in formation, development and multiplication of new virulence pathogen, so its challenges to researchers for identification of responsible different gene for it.

Leaf blight, weather parameters, standard week, cotton

From the present investigation it is concluded that epidemiology study revealed that, how the climatic condition affects on leaf blight on cotton, weather parameters were checked with late blight disease intensity in year 2020-21 and 2021-22. First leaf blight symptoms were appeared on 37th standard meteorological week in 2020-21 and 39th standard meteorological week in 2021-22 on cotton crop with minimum disease intensity i.e. 4.00 and 3.5 per cent. In year 2020-21 and 2021-22 maximum leaf blight intensity was recorded in First week of November (45th SMW) 37.50 and 39.00 per cents, respectively.

R. J. Chaudhari, M. M. Talpada, A. C. Detroja and S. N. Galani (2023). Effect of weather parameters in relation to occurrence and development of leaf blight (Alternaria macrospora) of cotton. Biological Forum – An International Journal, 15(8): 488-495.