Cotton stem weevil and its management.

摘要

Cotton stem weevil Pempherulus affinis Faust. has been reported as a major pest of "Cambodia cotton" in South India. Infestation occurs on 12 to 15 days old seedlings, which can cause the mortality up to 90%. Eggs are deposited on the soft and succulent collar region of the tender plant. Eggs, larval, pupal and adult periods of the pest were 6-9, 35-57, 9-12 and 12-50 days, respectively. Infestation occurs continuously throughout the season with a high infestation level of 95-100% during June. Eight chalcid species and three braconid parasitoids were recorded on P. affinis. Nadan, Bournon, Quebrandinoho, Verdao and Moco races were highly resistant. Inter cultural operations like earthing up, uprooting and burning of the badly infested plants would keep the pest under check. Hence, destruction of stalks in the second fortnight of May, which reduces the population substantially in the ensuing season, is recommended. Application of neem cake and neem oil, followed by earthing up at 25 days after sowing and drenching with chlorpyriphos 0.05% were effective.