Performance of organic and conventional programs for powdery mildew management on wine grapes in PA, 2011.

摘要

The test was conducted to evaluate the efficacy of organic and organic/synthetic rotational fungicide programs to control grape powdery mildew. Fungicide applications were made to top-wire-trained Traminette and Chambourcin vines that were planted randomly in each plot located at the Penn State Fruit Research & Extension Center vineyard, Biglerville, PA. The experiment was arranged in a randomized complete block design, with four replications. A standard insecticide maintenance program was separatelyapplied using an air-blast sprayer delivering 100 gal/A at 400 psi. A standard fungicide maintenance program provided season-long control of the common grapevine diseases other than powdery mildew. Treatments were applied using a Bean covered-boom dilute sprayer delivering 50-100 gal/A at 100 psi, depending on the canopy growth. Rainfall for Apr, May, Jun, Jul, and Aug was 11.35 in., 4.32 in., 1.42 in., 3.86 in., and 4.21 in., respectively. On 22 Aug powdery mildew incidence was rated on shoots and fruit clusters by visually determining the percent infected among 25 arbitrarily-selected shoots and clusters per plot. Severity (percent infection within a shoot or cluster) was rated using the Barratt-Horsfall scale and was converted to percent area infected using Elanco conversion tables. Data were analyzed using analysis of variance and mean separation was determined by the Fisher's Protected LSD test (P < 0.05) (SAS Institute Inc., Cary, NC).