Effectiveness of biological pesticides in control of soybean rust

Abstract

Soybean rust is a major disease limiting soybean production in many areas of the world. Previous studies and farmers have used chemical fungicides such as Mancozeb to control the disease, however, this is only effective for a short time since the causal fungi continue to develop resistance to the different chemicals. However, as yet in Uganda, no much work has been done to test the efficacy of bio-pesticides as an alternative to chemical fungicides on the occurrence of the severity of soybean rust The objective of this study was to determine the efficacy of the biopesticides use in the control of soybean rust. A completely Randomized Block designed experiment was set up at Makerere University Research Institute Kabanylo (MUARIK) with eight treatments and three replicates including; Pseudomonas fluorescens, Verticillium chlamydospora (Pochonia chlamydospora), Trichordema viride, Beauveria bassiana, Mancozeb, anustarAzoxystrobin, anusulf-sulphur and control with no fungicide applied. Data was collected on disease severity, plant height, leaf area and the grain yield after harvest and analysed using the Genstat 14th Edition. Results from the study indicate that Mancozeb is the most effective with the lowest disease severity 1.143, followed by anusulf at 1.267, followed by Trichoderma viride at 1.287, followed by anustar at 1.374, followed by Pseudomonas flurescens followed by Beauveria bassiana at 1.383, followed by control at 1.409 and the least effective being by Verticillium chlamydospora (Pochonia chlamydospora) at 1.427. Results also indicated that chemical fungicides generally performed better than the bio-pesticides although Trichordema viride, Pseudomonas fluorescens and Beauveria bassiana also lowered the rust disease severity as compared to the control. Mancozeb treated plants attained a significantly (P<0.05) higher plant height compared to other treatments while leaf area showed no significant differences among treatments. It is therefore recommended that further studies be conducted for more conclusive results on the efficacy of bio insecticides on soybean rust control.