Agricultural Science Digest - A Research Journal

Biotic and abiotic factors limit the productivity of blackgram including insect pests like leafhopper, Empoasca kerri, whitefly, Bemisia tabaci, tobacco caterpillar, Spodoptera litura, semilooper, Trichoplusia ni and bihar hairy caterpillar, Spilosoma obliqua.The high population of 3.49 whiteflies/leaf was observed during 39^thstandard week. Whitefly and leafhopper population with sunshine hours showed non-significant negative correlation while rainfall, temperature (minimum and maximum), relative humidity (morning and evening), and wind velocity showed a non significant positive correlation. The highest population of tobacco caterpillar, 3.83 larvae/m² was recorded during 40^th SW. Rainfall and wind velocity showed non-significant negative correlation while temperature (minimum and maximum), relative humidity (morning and evening) and sunshine showed a nonsignificant positive correlation with the population of S. litura. Maximum level of T. ni population 8.37 larvae/m² attained during 39^thSW. Population of T. ni had significant positive correlation with minimum temperature and evening relative humidity. The highest population of S. obliqua, 29.50 larvae/m² was recorded during 40^thSW. Rainfall and wind velocity with S. obliqua population showed significant negative correlation. Maximum level of coccinellids 2.36/m² was recorded during 39^thSW. Rainfall, wind velocity and sunshine showed non-significant negative correlation while temperature (minimum and maximum) and relative humidity (morning and evening) showed non-significant positive correlation.