The objective of this study was to verify the effect of garlic extract and vegetable oil in the control of downy mildew cv. Isabel (Vitis labrusca). Disease severity expressed as area under disease progress curve (AUDPC) and germination of the sporangia of its causal agent Plasmopara viticola were evaluated. The treatments tested consisted of 0; 5, 10, 15, 20, 25 or 30 mL L-1 of garlic extract added to 2.5 mL L-1 of vegetable oil, bordeaux mixture (1:1:100) and control. Mancozeb (2 g L-1) was used as a standard treatment in the germination test. In field conditions, there was reduction in severity of mildew with vegetable oil, and garlic extract from 20 mL L-1 potentiated such biocide action. The sporangium germination of P. viticola varied depending on the length of exposure to garlic extract, showing no efficient when compared to treatment with bordeaux mixture and mancozeb. Vegetable oil had no effect on sporangium germination of this pathogen.
Vitis labrusca; Plasmopara viticola; alternative control
