Use of advisory systems and plastic covering in the control of downy mildew on vines of São Paulo, Brazil.

anglais. The Northwest region of the State of São Paulo is one of the main producers of table grapes in Brazil. However, the climate of this region is highly favorable for fungal diseases during the growing season. The use of disease advisory systems and plastic covers are promising alternatives for rationalize the use of fungicides for disease control. Thus, the objective of this study was to evaluate the efficacy of the combination of advisory systems and plastic covering in the control of downy mildew (Plasmopara viticola) on vineyards of the Northwest region of State of São Paulo, Brazil. The experiments were carried out at the EMBRAPA - Tropical Viticulture Experimental Station, located in Jales, SP, Brazil. Three rows of 120 m of the seedless grape cultivar ?BRS Morena? (Vitis vinifera), spaced with 3.0 m between plants were conducted during 2012 and 2013 growing seasons. Half of the vineyard was covered with braided polypropylene plastic film installed over a metallic arc-shaped structure and the other half with black screen, with 18% of shading. The experimental design was randomized blocks composed of five treatments, with six repetitions per covered environment. The treatments were defined by the different grapevine downy mildew management : (CO) Control (no sprays against downy mildew); (CA) Conventional control (calendar); (BA) Advisory system 'Rule 3-10'; (MA25) Advisory system with low-infection efficiency - i0 > 25%; and (MA75) Advisory system with high infection efficiency ? i0 > 75%. According to the results, the plastic cover alone was not effective in controlling downy mildew. Under plastic cover, all advisory systems tested were as effective as the control provided by treatment calendar (CA), however, with 75% less fungicide application (MA75) than CA.

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