Influence of Abiotic Factors on Whitefly Population Abundance in Cotton

Whitefly started to infest cotton soon after planting in favourable weather condition. During November planting mean whitefly population were highest (6.9 whiteflies per 3 leaves) and slowly declined in successive planting dates. It was found that number of population were above ETL during the month of December, January and February. Maximum population were recorded in the month of February depending on the growth stage of the crop. Maximum temperature beyond 35°C, minimum temperature below 8°C and moderate to high rainfall was very much detrimental to successful population build up. The most favourable temperature was ranged in respect of min. temperature and max. temperature was ranged 12–30°C. Simple regression value reflects whitefly population were influenced to the tune of 70.8%, 69.5%, 35.3% and 75.4% in November, December, January and February month respectively. Whitefly population were negatively correlated with temperature (max. and min.), rainfall and relative humidity (max. and min.); while, positively correlated with sunshine hours, but during November planting relative humidity (max. and min.) was positively correlated and sunshine hours were negatively correlated. Thus adjustment of planting dates may be adjusted or suitable plant protection measure may be introduced according to the weather forecast