Efficacy of Bidens pilosa and Euphorbia hirta Extracts in Control of Bacterial Leaf Spot Disease of Solanum scabrum

Bacterial leaf spot disease incited by Xanthomonas campestris pv. vescatoria affects solanum plants worldwide and caused up to 40-70% yield loss of Solanum scabrum. Efficacy of Bidens pilosa and Euphorbia hirta leaf and root extracts and one synthetic chemical Ridomil® was evaluated for control of bacterial leaf spot in Solanum scabrum. The experiment was laid out in randomized complete block design with three replicates. Seedlings were inoculated with Xanthomonas campestris pv. vesicatoria isolated from diseased S. scabrum and then treated separately with test concentrations of 25%, 50%, 100% and 50 mg/ml 100 mg/ml and 200 mg/ml for water and ethanol extract respectively. The extracts reduced disease severity with the highest concentrations (100% and 200 mg/ml significantly lowering disease severity compared to other extracts and Ridomil®. Plants treated with high concentrations of extracts had high growth vigor when stem diameter, plant height and leaf weight were evaluated. Reduction in disease severity and promotion of plant growth could be due to presence of secondary metabolites with antimicrobial activity and growth promoting hormones in the extracts. From this study B. pilosa and E. hirta extracts can be used as an alternative to synthetic chemical to control bacterial leaf spot disease of solanum. Future studied should focus on isolating active compounds to be used in formulating pesticides.