Assessment of Quantitative Yield Losses Due to Chemical Intervention in Cabbage (Brassica oleracea var. capitata) Under Poly House Conditions

A field experiment was conducted in polyhouse with two treatments viz., protected and unprotected plots with plot size of 100 m2 each and further each treatment was divided into 13 quadrates with 1.5 X 0.5 m spacing. Protected treatment was kept protected from insect infestation by regular application of recommended pesticides and unprotected treatment was exposed to natural infestation throughout the crop growth. The mean reduction in plant height, weight of cabbage heads and head damage loss caused by insect pest infestation was 24.08 cm and 20.30 cm, 1.36 kg and 0.49 kg and 9.15 per cent and 76.15 per cent in protected and unprotected plots respectively. On the basis of significant mean difference observed in plant height, weight of cabbage heads and head damage lossbetween protected and unprotected plots, the quantitative losses estimated as15.73 per cent, 64.36 per cent, 87.74 per cent, respectively.