Formulation of weather-based criteria rules for the prediction of sucking pests in cotton (Gossypium hirsutum) in Punjab (original) (raw)

A study was conducted during 2005-06 to develop a weather―based forecasting model for sucking pest in Bt-cotton (Gossypium hirsutum Linn.). The population dynamics of jassid, whitefly and thrips with respect to meteorological parameters on Bt-cotton ('Ankur 651' during rainy (kharif) season 2005 and 'RCH 34' during rainy season 2006) under 3 dates of sowing was conducted during crop seasons at research farm of the University, Ludhiana. The results revealed that a decrease in maximum temperature (6-7°C from normal of>38°C) and minimum temperature (4-5°C from normal of >27°C) and sunshine hours (5-7 hr from normal of >8 hr) favour the population build-up of cotton jassid (Amrasca bigutulla Shir). Whereas an increase in temperature (maximum temperature >32°C; minimum temperature >25°C) and sunshine hours (>9 hr) coupled with decreased relative humidity favoured the build-up of cotton whitefly (Bemisia tabaci Genn.). Of these parameters, the contribution of increase in the number of sunshine hours has been significant with respect to its build-up. Cotton thrips (Thrips tabaci Lindi.) appeared on cotton during its early vegetative stage and ceased its activity with the onset of south-west monsoon. Peak population of thrips was recorded as soon as the maximum and minimum temperature crossed 39 and 25°C and morning and evening relative humidity was below 55 and 35%, respectively along with more than 9 hr of sunshine. On the contrary a decrease in temperature and sunshine hours and increase in relative humidity coupled with a heavy rainfall led to cessation of thrips activity in cotton.