MANAGEMENT OF SUCKING AND CHEWING PESTS OF HILL COTTON, Gossypium arboreum Linn. IN JHUM CULTURE

Abstract

Hill Cotton (Malvaceae, Gossypium arboreum Linn.) is an important cash crop grown by the tribal farmers on hill slopes in the Chittagong Hill Tracts, usually as a component crop in Jhum cultivation (traditional shifting cultivation). Farmers sow the cotton seed together with other crops, eg. rice, maize, ginger, turmeric, banana, sesame, cassava and various fruits (Farid and Mujibullah.1990). A variety of pests are responsible for reducing the growth and yield of hill cotton. Among the insects pests sap-sucking species like cotton aphid (Homoptera. Aphididae, Aphis gossypii Glover), Jassid (Homoptera, Cicadellidae, Amrasca biguttula Ishida), Whitefly (Homoptera, Aleyrodidae,Z?t'me‟.s/a tabaci Gennadius), Red Cotton Bug (Hemiptera. Pyrrhocoridae, Dysdercus cingulatus Fabricius) and chewing insects like the spotted bollworm (Lepidoptera, Noctuidae, Earias vittella Fabriciav) are the most damaging (Bohlen, 1984/85). This study evaluated the effect of two pesticides and a fungicide on the productivity of hill cotton in Jhum cultivation. A randomized complete block design experiment was conducted in the experimental fields of Hill Cotton Research Station, Balaghata, Bandarban Hill District to compare the effectiveness of a botanical pesticide (Neembacidin) and a synthetic organophosphorus insecticide (Roxiban 20EC) for the management of the infestation and damage by the above insect pests. Both products significantly reduced the number of psets; however, Neembacidin (derived from the tree. Azadirachta indica A.Juss, Meliaceae) provided better control of insect pests than Roxiban 20EC. The effectiveness of fungicide, Vitavax-200. was also evaluated for its role in cotton seedling emergence and mortality. Use of Vitavax-200 was found to have no effect on seedling emergence, but it significantly reduced subsequent seedling mortality in treated fields in comparison with the untreated controls. The results of the present experiment denoted that timely use of a fungicide, Vitavax-200 and a botanical pesticide, Neembacidin may prove to be of immense practical value for improving the production of hill cotton. Gossypium arboreum Linn, in the Chittagong Hill Tracts.