ESTIMATION OF YIELD LOSSES IN BRASSICA DUE TO INSECT PESTS

摘要

An experiment was carried out to assess the yield losses due to insect pests in Brassica (B. juncea, B. rapa var. yellow sarson, B. rapa var. toria and B. rapa var. brown sarson) during winter of 2011-12,2012-13 and 2013-14 at the Pulses and OilseedsResearch Station, Berhampore, Murshidabad, West Bengal. The study was conducted in two sets i.e., protected/ sprayed and unprotected, in a randomized block design, with four replications. Data on the infestation and seed yield were recorded at weekly interval and at harvest, respectively.. The loss in the seed yield due to mustard aphid (Lipaphis erysimi Kalt.) and sawfly (Athalia lugens proximo Klug.) infestation varied from 34.62 to 59.33%. The pooled data revealed that B. juncea (var. NRCDR-2) suffered less damage due to aphid (16.83 aphid/ 10 cm shoot of plant) and sawfly (6.48 larvae/ 10 plants) in the unprotected plots and thereby registered minimum seed yield losses of 34.62%. The overall findings confirmed the heavy losses to late sown brassicacrops due to prolonged feeding of mustard aphid and sporadic attack of sawfly. Therefore, application of insecticides has been recommended in late sown rapeseed-mustard crop to reduce the attack of aphid.