Evaluation of fungicide programs for control of grapevine powdery mildew, 2009.

摘要

The experiment was conducted in a vineyard of vertically-shoot-positioned, 4-yr-old grapevines located at Geneva, NY. Treatments were applied to four-vine plots arranged in a randomized complete block design with four replications. Sprays were appliedwith a hooded-boom sprayer at 300 psi (2069 kPa) in a volume of 50 gpa (467 l/ha) prebloom (sprays #1, 2) and 100 gpa (935 l/ha) subsequently. In addition to the variable treatment regimes, all plots received the following materials (rate/A) to controldowny mildew, black rot and Japanese beetle: Penncozeb 75DF (4.0 lb) on 29 May, 10 and 22 Jun; Penncozeb 75DF (4.0 lb), Ridomil Gold EC (8.0 fl oz) and Danitol 2.4 EC (16.0 fl oz/A) on 6 Jul; Ridomil Gold EC (8.0 fl oz/A) and Danitol 2.4 EC (16.0 fl oz/A) on 20 Jul; Phostrol (4.0 pt/A) and Danitol 2.4 EC (16.0 fl oz) on 3 Aug; and Ridomil Gold EC (8.0 fl oz) on 17 Aug. Disease assessments were made on 25 clusters from the center of each plot on 31 Aug and on 25 leaves from the center of each plot on 17Sep. Disease incidence was calculated as the percentage of leaves or clusters showing any infection; disease severity (area symptomatic) was rated using the Barratt-Horsfall scale and converted to percentage values using Elanco conversion tables. Rainfall amounts in the Geneva area were 3.55, 5.09, 3.48, 3.15 and 1.61 inches for May, Jun, Jul, Aug and Sep respectively.