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Southern blight epidemic: What management options are available to smallholder Common bean farmers in Uganda?

Pamela Paparu: National Agricultural Research Organization -National Crops Resources Research Institute

<div>Southern blight caused by <em>Sclerotium rolfsii</em> Sacc. has become a serious disease of common bean in Ugandan. This being a relatively new disease, farmers are not using any management strategies to reduce the impact of the disease on yield. To identify resistant varieties, we evaluated over 500 lines from the Andean Diversity Panel, 132 ALBs (SER 16 x <em>Phaseolus coccineus</em>), lines from Fusarium and Pythium root rot nurseries and Ugandan local germplasm for their reaction to <em>Sclerotium rolfsii</em>. We also validated in farmers’ fields root rot management practices such as seed treatment with fungicide (mancozeb and metalaxyl-M), use of NPK 17:17:17 and farm yard manure, and a combination of seed treatment with either of the fertilizers. Untreated seed of the susceptible variety CAL 96 acted as a control. We identified 4 lines with considerable resistance to southern blight, and these are currently being used in our crop improvement programme. Seed treatment and soil fertilization significantly increased seed germination, plant stand at harvest and yield. Seed treatment in combination with NPK 17:17:17 and farm yard manure application increased seed germination by 5-20%, plant stand at harvest by up to 10% and yield by 17-33% over control. As breeding efforts to produce a resistant variety continue, we recommend the use of fungicide seed treatment and soil fertilization to reduce the impact of southern blight and improve yield of common bean in smallholder farms in Uganda.</div>