This work aimed to evaluate the effect of chitosan on the control of fungi Elsinoe ampelina and Plasmopara viticola, the causal agents of downy mildew and anthracnose in grapevines, respectively. The concentrations of 0, 20, 40, 80 and 160 mg L-1 chitosan were used in the following trials: mycelial growth, spore germination, and experiment in field conditions. For the last two trials standard treatments with mancozeb and bordeax mixture were added. There was a reduction in E. ampelina mycelial growth and the highest chitosan concentration (160 mg L-1) decreased by 57% the fungus development at 192 hours after incubation. In the germination tests, the concentration of 160 mg L-1 chitosan reduced spore germination in E. ampelina by approximately 98% and P. viticola by 60%, not differing from the treatments with bordeaux mixture and mancozeb. In the field trial the highest chitosan concentrations (80 and 160 mg L-1) decreased anthracnose severity between 93 and 81%. For downy mildew, the concentration of 160 mg L-1 decreased the disease by approximately 81%. Based on these results, chitosan has a great potential for the control of downy mildew and anthracnose in grapevines.
Vitis labrusca; alternative control; downy mildew; anthracnose; vines; fruit trees of temperate climates
