Effect of abiotic factors on population of aphid and damage by shoot & fruit borer in okra during summer and kharif season at Anand in Gujarat

Abstract

A field experiment was conducted at Anand Agricultural University, Anand, Gujarat to study the impact of weather variables on population dynamics of aphid, Aphis gossypii and shoot & fruit borer, Earias vittella in summer and kharif okra for two consecutive years (2005-06 and 2006-07). Peak activity of aphid population was found during 12th & 14th and 13th & 15th Meteorological Standard Week (MSW) whereas, the peak infestation to fruits due to E. vittella observed in the 13th & 15th and 29th & 32nd MSW during summer and kharif season, respectively. Bright sunshine hours, temperature (maximum and minimum), vapour pressure (morning and evening) and wind speed had significant positive effect on population of aphid during summer season, while Bright sunshine hours, maximum temperature and temperature range showed significant negative impact with aphid population during kharif season. Maximum and minimum temperature had significantly negative effect, while morning and evening relative humidity significant positive effect on fruit damage due to E. vittella during kharif season. However, per cent fruit damage showed significant positive impact with BSS, temperature (maximum and minimum) and vapour pressure deficit (morning and evening) during summer season.