Vol. 11, Special Issue 3 (2022)

Author(s):
O Shaila, S Ramesh, S Srinivas Reddy, K Vijaya Laxmi, M Sujatha and Ch. Damodar Raju

Abstract:
Field experiment was conducted to study the seasonal incidence of various insect pests and diseases of mustard crop in variety, NRCHB:101 during rabi 2020-2021 at Regional Agricultural Research Station (RARS), Palem, Nagarkarnool district, Telangana State. Incidence of mustard aphids (Lipaphis erysimi Kalt.) started from 50^th SMW (2.83 aphids/plt) and attained their peak during 51^st (49.27 aphids/plt) to 4^th (58.08 aphids/plt) SMW. The aphid appeared at its peak at flowering stage of crop, which was synchronized with the activities of predatory coccinellid beetles, Coccinella septempunctata. The first appearance of diamond back moth was during the vegetative stage of the crop and the peak incidence of DBM (12.31 larvae/plt) was observed at 49^th SMW. The leaf webber (Crocidolomia binotalis Zeller) incidence was noticed during the entire crop stage. While, the incidence reached to its peak (3.76 webs/plt) at 52^nd SMW. Among all the insects pests noticed during the crop period mustard saw fly incidence was comparatively less. The correlation studies between different weather parameters (Maximum temperature (T_max), Minimum temperature (T_min), Morning relative (RH I) and Evening Relative Humidity (RH II) and population of major insect pests revealed that aphids are positively correlated with T_max (r=0.460), T_min (r=0.147) and negatively correlated with RH I (r=-0.042) and a negative significant association with RH II (r= -0.752) at 0.05 level was noticed and coccinellids & are positively (r=0.364, r=0.193) correlated with temperature and negatively r=-0.221, r=-0.488 correlated with relative humidity. While the leaf webber (r=-0.090, r=-0.397 & r=-0.658, r=-0.282) and saw fly (r=-0.247 & r=-0.013, r=-0.408) incidence was negatively correlated with temperature and RH while, saw fly population had a negative significant (r=-0.707) association was observed with RH II. However, the incidence of diamond back moth negatively correlated with the temperature (r=-0.505, r=-0.090) and morning relative humidity (RH I) (r=-0.014) while, positive significant (r=0.769) association with evening relative humidity (RH II) was observed.