Incidence of cotton bollworm, Helicoverpa armigera (Hubner) on field crops

Incidence of Helicoverpa armigera (Hubner) on important field crops at Raichur viz., cotton, pigeonpea, sunflower, chickpea and sorghum evaluated during 2009–10 revealed that the pest commenced its activity in the last week of September and remained active up to first week of January in cotton with a peak during 1^st to 3^rd week of November. In pigeonpea, the larval activity was noticed from second week of October to first week of January with two peaks, one on third week of October and second on second week of November. On sunflower it was from third week of October to third week of November with a peak on first week of November. In chickpea, it was noticed from last week of November to second week of February with a peak on third week of December. However, no larval population was noticed on sorghum. Among the weather parameters, maximum and minimum temperature recorded positive but nonsignificant correlation with larval incidence on all crops except chickpea whereas, rainfall and morning relative humidity recorded negative but nonsignificant correlation with larval incidence in all the crops.