Effects of wine grape cultivar, application conditions and the winemaking process on the dissipation of six pesticides
Pesticide residue in primary products is an important issue for producers and consumers, even though little information is available on the effect of application conditions on residue persistence and the transfer to primary elaborated products. During the 2012 season, field and laboratory studies were conducted to determine the dissipation of lambda-cyhalothrin, buprofezin, pyrimethanil, tebuconazole, imidacloprid and acetamiprid in Sauvignon blanc and Pinot Noir cultivars and their residue dynamics during the winemaking process. Half-life values (DT50) for each pesticide applied alone and as a tank mix of all pesticides were similar and had averages of 6.4, 14.0, 19.7, 26.0, 14.5 and 13.4 days for lambda-cyhalothrin, buprofezin, pyrimethanil, tebuconazole, imidacloprid and acetamiprid, respectively. The grape cultivar did not affect pesticide DT50. All pesticides were transferred from the raw material (grape) to red and white wines except lambdacyhalothrin. The transfer factors of buprofezin, tebuconazole pyrimethanil, imidacloprid and acetamiprid ranged from 3 to 23% in red wine and 9 to 30% in white wine. Alcoholic fermentation, pressing (through pomace) and malolactic fermentation were the steps in which the greatest residue losses occurred in red wine, whereas pressing (through the grape and stem), alcoholic fermentation and clarification with bentonite had the greatest residue loss in white wine. In both cases, bottled wine showed substantial residue reduction after ten months.