The aim of the present study was to evaluate the effect of aqueous extract of chinaberry (Melia azedarach) in the control of Plasmopara viticola. For the germination test of sporangia of the oomycete, concentrations of 0, 5, 10, 15, 20 and 25 mL L-1 of aqueous extract of chinaberry (EC) were used, as well as treatments with mancozeb and bordeaux mixture. The experiment in the greenhouse and field involved concentrations of 0, 30, 40 and 50 mL L-1 of EC (1:10 w/v) and a treatment with bordeaux mixture (1:1:100 ). In the second experiment in the field the treatments were: 0, 10, 20, 30, 40 and 50 mL L-1 of EC with an added 2.5 mL L-1 of vegetable oil, the bordeaux mixture and an absolute control. In the germination test, there was highest inhibition of P. viticola at 2 hours after incubation at 20º C, for the 20 and 25 mL L-1 concentrations of the EC, with a reduction of 66.5 and 62.0%, respectively. In the greenhouse conditions, the EC at a concentration of 40 and 50 mL L-1 showed a reduction of 70.0% and 86.0% of the disease, respectively, while the same concentrations in the first cycle of the field experiment showed a decrease of 34.0% and 31.0%, respectively. However, in the second cycle, the use of vegetable oil as an adjunct masked the effect of the EC, and the isolated application of vegetable oil decreased the area under the disease progress curve (ADPC) by 76.3%, similar to results obtained with all concentrations of EC and with the bordeaux mixture.
Vitis vinifera; lily-of-india; agroecology; Plasmopara viticola; Melia azederach