Dosage Adjustment for Pesticide Application in Vineyards

Abstract

Traditional pesticide application in grapevines causes large losses to the air and the ground, particularly in early to mid-season applications. Traditional application rates do not differ much according to the season. Canopy size varies as growers choose different row widths, varieties, and trellis designs; however, pesticide labels for vineyard sprays persist in using ground area based application rates. That is why dosage adjustments according to the canopy characteristics have been developed. In the trial described in this article, three adjustment methods, unit canopy row (UCR) (Australia), DOSAVIA (Spain and U.S.), and leaf wall area (LWA) (Germany and Belgium) are compared with traditional American application rates. This article presents the methodology and results of the study. In total, three trials were completed. Results demonstrated that at the early growth stage, deposits with the DOSAVIA and LWA methods were not significantly different from that of the traditional method, and deposits were not different from each other among DOSAVIA, LWA, and UCR (application rates were 327, 281, 234, and 187 L ha-1 for the traditional, LWA, DOSAVIA, and UCR methods, respectively). Concerning the uniformity of distribution, UCR achieved the best results in the early growth stage, followed by LWA. At the middle growth stage, LWA and the traditional method achieved similar results, while deposits using DOSAVIA and UCR were not significantly different. At the middle growth stage, the application rate was increased to 700 L ha-1 for the traditional method and to 560, 327, and 374 L ha-1, respectively, for LWA, DOSAVIA, and UCR. The application rate was increased significantly according to the hugely changed canopy size. The LWA method achieved the best results in terms of deposits and uniformity of distribution. At the late growth stage, the traditional method achieved the highest deposits, while LWA and DOSAVIA achieved similar deposits. The lowest deposits in the canopy occurred with DOSAVIA and UCR. The results showed a high potential for reducing application rates using alternative methods compared with the traditional method. This article discusses only the deposits and coverage rate. In the next few years, biological efficacy trials are planned to confirm the advantages of the selected dosage adjustment methods.