Seasonal Variation in the Population of Whitefly (Bemisia tabaci) and Incidence of Web Blight in Black Gram, Vigna mungo (L.) Hepper under Sub-mountainous Region of Punjab

The increasing incidence of whitefly (Bemisia tabaci) and web blight disease (Rhizoctonia solani Kuhn) cause huge yield loses in black gram. Keeping this in view, a study was conducted at research farm of Dr. D.R. Bhumbla Regional Research Station, Ballowal Saunkhri, (SBS Nagar), Punjab during kharif 2019 and 2020 to ascertain the impact of different meteorological parameters on the occurrence and development of whitefly population and web blight disease on black gram. The whitefly attained peak population of 12.88 and 16.56 whiteflies/leaf in 38^th SMW during 2019 and 2020 respectively. Among all weather parameters, maximum temperature showed significant positive correlation with whitefly population during 2019 (r=0.71) and 2020 (r=0.73) respectively. In case of web blight, maximum disease severity and PDI (54.7 and 65.9%) were in 34^th SMW in 2019 while in 2020, maximum disease severity (42.0%) was in 38 SMW. A positive correlation of disease severity and per cent disease index was found with maximum temperature and relative humidity (morning) during both crop seasons. The results will help in formulation of insect-pest and disease monitoring system followed by sustainable integrated pest and disease management programme.