Influence of Weather Parameters on Foliar Diseases of Sesame (Sesamum indicum L.) in Coastal Ecosystem of West Bengal, India

Sesame is one of the most important oilseed crops in India due to mainly its high quality seed oil and antioxidant properties. Occurrence of foliar diseases, like Alternaria leaf spot and Cercospora leaf spot has become a major constraint in recent years for successful and profitable cultivation of sesame. Field experiments were conducted with sesame var. savitri in a factorial randomized block design with three different dates of sowing with 15 days interval and two different plant protection situations (Protected i.e., treated with disease control protocols and unprotected i.e., control), replicated four times, during two consecutive summer seasons of 2018 and 2019 at Agricultural Experimental Farm, Institute of Agricultural Science, University of Calcutta, Baruipur, South 24 Parganas. The diseases incidence was estimated and correlated with the weather parameters. The average of weather parameters viz., maximum temperature, minimum temperature, relative humidity (morning), relative humidity (evening) and rainfall prior to seven days of disease appearance were considered for study the correlation between the weather factors and the disease. In 2018, disease incidences of the plants shown at third date of sowing (26th April, 2018) in both the protected and unprotected plots had significant (P=.05) but negative correlation with maximum temperature. For plants sown at first date of sowing (27th March, 2018) in 2018 had disease incidences significantly (P=.05) and positively correlated with minimum temperature. However, in 2019, except for the relation between disease incidences in the unprotected plots and maximum temperature, all other disease-temperature correlations were non-significant. Disease incidences were positively and significantly correlated with relative humidity (both morning and evening) in all dates of sowing irrespective of experimental years, except with morning relative humidity at first date of sowing in first year. Total rainfall was positively and significantly correlated with disease incidences at all dates of sowing in 2018; however, such relation was non-significant in 2019.