Exploitation of Selected Plant Based Insecticides for Field Management and Control of Aphids in Organic Cabbage Production

Abstract

Large colonies of cabbage aphids are capable of stunting and or killing small plants. They are also capable of contaminating harvested crop. The use of biodegradable botanicals for pest control is now considered one of the best alternatives to synthetic pesticides; and they are known to be safer and ecological friendly. This study was conducted to evaluate the effect of three plant based extracts and their mixtures for their efficiency in the control of aphids in a cabbage field. Extracts from Azadirachta indica, Chrysanthemum cinerariifolium, Quassia amara, their mixtures and a positive and negative control were used. Two field studies were carried out at different periods (spring and late summer studies). Decline in aphid infestation was determined by recording number of infested plants per plot and the average number of aphids per plant; before and after each treatment application. All extracts and their mixtures decreased aphid population significantly (p<0.001) in both seasons. A mean pest population decline of 86.78% and 85.48% for number of aphids/plant was recorded in the spring and late summer study respectively; and an 86.00% and 85.48% decline in number of plants infested for the spring and late summer study respectively. Decline in infestation produced by all extracts was comparable to that of the synthetic insecticide used for the study.

Keywords: Cabbage, Organic pest control, Bio-pesticide, Azadirachtin, Pyrethrin, Quassin, Plant extracts.