The aim of this study was to evaluate the effect of aqueous extract of chinaberry (Melia azedarach L.) on Elsinoe ampelina, the etiological agent of grapevine anthracnose, and on the disease control. For the trials of mycelial growth, sporulation and conidium germination, the concentrations 0, 10, 20, 30, 40 and 50 mL L-1 extract were used, besides standard treatments with bordeaux mixture and mancozeb. Under field conditions, an experiment was conducted in a commercial vineyard for two consecutive cycles (2009/2010, 2010/2011) to evaluate increasing concentrations of extract and vegetable oil (2.5 mL L-1), in addition to an absolute control (without treatment) and standard treatment with bordeaux mixture. Concentrations equal to or higher than 20 mL L-1 extract led to complete inhibition of sporulation. The concentration of 50 mL L-1 decreased by 99.4% the colony diameter and did not differ from the treatment with bordeaux mixture, besides reducing conidium germination by 84.8 and 90.8%, compared to control, at 12 and 24 hours after incubation. In the first year of the experiment in the field, there was a negative linear effect of extract concentrations on anthracnose severity. However, in the second year, the use of vegetable oil as adjuvant masked the extract effect. The isolate application of vegetable oil reduced AUDPC by 64.0%, which is similar to the results obtained with all concentrations of chinaberry extract and the standard treatment with bordeaux mixture.
chinaberry; agroecology; plant extracts; organic production
