Evaluation of fungicides for control of foliar and fruit diseases in Niagara grapes, 2012

摘要

The experiment was conducted in a mature vineyard at the Clarksville Horticulture Experiment Station in Clarksville, MI. Vines were spaced at 6 x 10 ft and were cordon trained and hand pruned. Treatments were applied to 4-vine plots and were replicated 4 times in a randomized complete block design. Sprays were applied using a Farmco research skid-mounted sprayer equipped with six 5 gal tanks, a 12-volt 3.8-gpm diaphragm pump set at 55 psi, and an XR TeeJet 8002VS nozzle on a 5-ft spray boom. Spray volume was 50 gpa on 6 Jun and 75 gpa thereafter. Spray dates and approximate phenological stages were as follows: 6 Jun (5-10 inch shoots), 22 Jun (1st post-bloom), 6 Jul (2nd post-bloom), 20 Jul (3rd post-bloom; bunch closure), 8 Aug (4th post-bloom). Disease ratings were conducted on the following dates: 11 Sep (powdery mildew, downy mildew and black rot on leaves) and 9 Oct (black rot and Phomopsis on clusters). In all cases, 25 random samples per plot were selected for rating. Disease evaluation included incidence (% clusters or leaves with any level of infection) and severity (% cluster or leaf infected on diseased samples only). Overall severity in each case was calculated as (incidence x severity)/100. Treatments were observed for phytotoxicity throughout the season.