Evaluation of Agronet Covers to Reduce Pesticide Application for Yield Improvement and Profitability for Small Scale Cabbage (Brassica oleraceae var. capitata) Growers

Abstract

Poor returns from open field cabbage (Brassica oleraceae var. capitata) production in sub-Saharan Africa are attributed to compromised yield due to high pest infestation. With chemical control measures becoming increasingly uneconomical and hazardous, relatively cheaper and eco-friendly alternative technologies are imperative. Two trials were conducted at the Horticulture Research and Teaching Field, Egerton University, Kenya to assess the yield and economic benefits of using agronet covers against major insect pests of cabbage. A randomized complete block design with six treatments replicated five times, was used. The treatments comprised of 0.4 mm and 0.9 mm pore diameter agronet covers maintained either by (i) opening thrice a week between 9.00 am and 5.00 pm or (ii) permanently covered except during routine crop maintenance, unprotected cabbage sprayed with insecticide and unprotected cabbage without any insecticide application (control).2 Agronet maintained permanently covered significantly reduced populations of cabbage aphids, diamondback moth, cabbage looper, mites, and leaf miners at P=0.05. Agronet covers reduced insecticide sprays per crop cycle from 11 to 1 and improved marketable cabbage head numbers by between 15.0-43.5% compared to the control and 2.1-27.3% compared to spraying with insecticides. Marketable head weight was higher by between 28.7-130.1% under agronets compared to the control and by 9.3-95.4% compared to spraying with insecticides. The highest cabbage marketable yields and net income on sales were obtained under the 0.9 mm pore diameter agronet maintained permanently covered which gave the highest cost benefit ratio of 1:17.1 in season one and 1:26.2 in season two. These results present permanent use of 0.9 mm pore diameter agronets as a viable technology in reducing insect pest infestation and cost of cabbage production. This is achieved through reduced pesticide use with a potential of contributing towards environmentally safe and profitable cabbage production by small-scale growers in sub-Saharan Africa.