Efficacy of aqueous extracts of neem, garlic and chili pepper fruit against diamondback moth, cabbage aphid and cabbage looper

Abstract

Biopesticides have potential benefits when used in Agriculture; they are inherently less harmful and environmentally safe, target specific, naturally and quickly decomposable and usable as a component of IPM. A field experiment was carried out during the first rainy season of 2021 in MUARIK in Wakiso district in central Uganda to investigate the efficacy of neem, garlic and Red chili pepper in controlling Diamondback moth(Plutella xylostella), Cabbage aphid(Brevicoryne brassicae) and Cabbage looper(Trichoplusia ni).A Randomized Complete Block Design of six treatments(300g of pounded neem leaves in four liters of water,300g of pounded garlic cloves in 4 liters of water,300g of pounded chili pepper, 300g mixture of pounded Neem,garlic and Chili pepper in a ratio of 1:1:1 in 4litres of water, Cypermethrin and control(untreated) was used in the experiment. Plant height, leaf area, DBM damage count per plant, DBM leaf damage score, Cabbage looper count per plant, Cabbage looper leaf damage score, Aphid count score and Cabbage head weight at harvest were measured to assess the effect of the biopesticides on the damage caused by the pests and their effect on the yield of Cabbage. Data was analyzed using RStudio software and graphs were generated from excel. Plant height varied significantly among the treatments (p˂0.001), plants treated with cypermethrin were the tallest which was followed by neem,garlic, Chili, Neem+Garlic+Chili and the control with the shortest plants. The leaf area also varied significantly (p˂ 0.001) with time after transplanting among the treatments Cypermethrin treated plants had the largest leaf area which was followed by neem+chili, Neem+Garlic+Chili and the control .DBM larval count and leaf damage score varied significantly(p˂0.001) among the treatments Cypermethrin treated plants had the lowest DBM larval count and damage score, this was followed by neem, Chili, garlic, Neem+Garlic+Chili and the control had the highest larval count and damage. The Cabbage aphid count also varied significantly (p˂0.001) among the treatments with The control plants having the highest aphid count, cypermethrin had the lowest aphid count which was followed by neem,Garlic,Chili and Neem+Garlic+Chili. The Cabbage looper larval count and damage score varied significantly (p˂0.001) among the treatment. Chili pepper had the highest larval count and leaf damage score which was followed by the control plot and Cypermethrin had the lowest larval count and damage score followed by Neem+ Garlic+ Chili, Neem and garlic. The average marketable yield did not vary significantly among the treatments. The experiment showed that the biopesticides have the potential to control major Cabbage