Effect of fungicides and biological products in controlling rust and gray mold in grapevines

Grape rust and gray mold are diseases in grapevines with high destructive potential. In this study, the effectiveness of different fungicides and biological products in controlling these diseases was evaluated using the cultivar “Niágara Rosada” in the municipality of Louveira-SP, from February to April 2017. A randomized block design was used, with 10 treatments and four replicates and five plants per plot. Each treatment was applied nine times at weekly intervals, with application volumes in the range of 400–1000 L/ha. The evaluation criterion for rust was the severity, based on the percentage of leaf area affected by the disease (0 to 100%), whereas gray mold was evaluated using the incidence of diseased bunches (0 to 100%). All treatments were effective in controlling both diseases and significantly reduced the disease incidence in the experimental plot compared with that in the control plots. The best rust control was obtained by treating the plants with boscalide+pyraclostrobin (1 L c.p./ha), which was superior to fluxapyroxade+pyraclostrobin (0.5 L) + Bacillus amyloliquefaciens (0.5 kg), B. amyloliquefaciens (0.5 kg), Melaleuca alternifolia essential oil (1.5 L), and dimoxystrobin+boscalide (1 L). The plants treated with fluxapyroxad+pyraclostrobin (0.5 L) + B. amyloliquefaciens (0.5 kg) had a lower incidence of gray mold than did those treated with dimoxystrobin+boscalide (1 L), boscalide+kresoxim methyl (0.5 L), and piremethanil (1.5 L). These results suggest that the use of M. alternifolia essential oil and B. amyloliquefaciens may represent an important tool for the management of rust and gray mold in grapevines.