Evaluating the efficiency of different methods to control yam leaf blight caused by curvularia eragrostides
Avaliação da eficiência de diferentes formas de controle da queima das folhas do inhame causada por curvularia eragrostides
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Leaf blight, caused by Curvularia eragrostides, can compromise the production of yam (Dioscorea spp.), a crop of extreme importance for the northeast region of Brazil. Natural products have been efficient in controlling plant diseases due to their fungitoxic action or to the presence of eliciting compounds, reducing the use of pesticides. The objective of this study was to evaluate the effect of different methods to control yam leaf blight caused by C. eragrostides. Sporulation of the fungus was analyzed in Petri plates containing PDA medium plus the following products: “manipueira” (40%); mint oil (100 μL/mL); garlic, ‘São Caetano’ melon and yam leaf extracts (20%); Ecolife® (2%); Trichoderma sp. (2.0 g.L-1), and acibenzolar-S-methyl (0.15 g.L-1 and 0.3 g.L-1), separately. Control treatment consisted of a plate containing PDA medium without addition of products. The preventive effect of products on the disease development in vivo was assessed with treatments selected in the in vitro test. In the in vivo experiment, yam plants cv. ‘Da Costa’, 45 days old, were sprayed with the products selected in the in vitro test at 48h and 72h before inoculation of the pathogen and mint oil (100 μL); garlic and yam leaf extracts (20%); Trichoderma sp. (2.0 g.L-1); acibenzolar-S-methyl (0.15 and 0.3 g L-1), and water (control). All natural products inhibited C. eragrostides sporulation. The best severity reduction was provided by Trichoderma sp. applied at 72h before inoculation of the pathogen (51%), followed by mint oil at 48h (41.4%) and 72h (31.5%), Trichoderma sp. at 48h (31.5%) and acibenzolar-S-methyl 0.3 g.L-1 at 72h (25.5%). The inoculation time influenced the disease severity according to the tested product. Trichoderma sp. was the treatment that most reduced the disease severity (51%) and can be recommended to integrate yam leaf blight management strategies.