Effect of transplanting dates on the incidence of Pieris brassicae Linn. and extent of losses in cabbage under dry temperate conditions of Himachal Pradesh

摘要

Cabbage butterfly, Pieris brassicae Linn. was recorded as the most serious pest of cabbage in the Sangla valley of Himachal Pradesh. It appeared in the first week of May, immediately after transplantation of cabbage. The infestation of P. brassicae varied through out the season. Higher incidence of P. brassicae was recorded in cabbage crop transplanted during last week of April and second fortnight of May. The incidence of P. brassicae was very low in cabbage transplanted after mid-June. However, low temperature and frost injury at the time of crop maturity resulted in poor cabbage yield. Significantly higher marketable cabbage yield was recorded in June second week (267.47 q/ha) and May second week (260.07 q/ha) transplanted crop. The yield losses due to P. brassicae were almost similar in all the transplanting dates (25.83 to 47.06 q/ha), except in the crops transplanted after First week of June. Yield losses due to other factors (diseases and abiotic stresses) were maximum in June third week (98.50 q/ha) and June fourth week (108.75 q/ha) transplanted crop. Crop transplanted during second week of June in spite of suffering losses due to P. brassicae (15.19 q/ha) and other factors (21.56 q/ha) matured in time and recorded maximum cabbage yield.