Effect of weather parameters on incidence of Helicoverpa armigera (Hubner) Infesting soybean

An investigation on effect of weather parameters on incidence of Helicoverpa armigera infesting soybean (var. Gujarat Soybean – 4) was carried out at Main Oilseeds Research Station, Junagadh Agricultural University, Junagadh during Kharif, season of 2023. The activity of H. armigera commenced from 32nd SMW (1st week of August) and continued till 42nd SMW (3rd week of October) with a population of 0.32 to 2.81 larvae/plant. The peak (2.81 larvae/plant) incidence was recorded during the 37th SMW (2nd week of September). The activity of H. armigera resulted into leaf damage which ranged from 3.06 to 26.91 per cent during 32nd SMW (1st week of August) to 42nd SMW (3rd week of October) with highest (26.91%) damage during the 37th SMW (2nd week of September). There was no further damage after 43rd SMW. The correlation analysis revealed that minimum temperature and morning vapour pressure had significant positive association with the population of H. armigera and leaf damage in case of soybean.