Management of snap bean insect pests and diseases by use of antagonistic fungi and plant extracts.

Abstract

Use of synthetic pesticides reduces the competitiveness of Kenyan snap bean pods due to stringent regulations by importers as a result of presence of chemical residues. This study was conducted to determine the effectiveness of local biopesticides in managing insect pests and diseases of snap beans. Field experiments were set up in farmer's field where Trichoderma spp. and Paecilomyce spp. and plant extracts from turmeric, garlic, ginger and lemon were applied weekly as foliar sprays. Plant extracts reduced the population of whiteflies and thrips by up to 58% and 41% while antagonistic fungi had a corresponding 30% and 18% reduction, respectively. Trichoderma spp. reduced severity of angular leaf spot (37.5%), rust (67%) and anthracnose (20.7%). Plant extracts and antagonistic fungi increased marketable pod yield by 25.6% and 17.3%, respectively. Results demonstrated that local environments are potential sources of biopesticides that can be exploited for integrated management of pests and diseases.