Evaluation of fungicides for control of gummy stem blight on watermelon, Georgia 2017

摘要

Fungicides were evaluated for their efficacy to manage gummy stem blight. The experiment was conducted at the Tifton Vegetable Park at Tifton, GA. Watermelon (cv. Sangria) were transplanted onto single row beds covered with 18-in. white plastic mulchon 29 Jun. Beds were on 6-ft centers with 1-ft plant spacing within rows. Plots were 15-ft long with and used 10-ft unplanted borders between plot ends. The trial was arranged in a randomized complete block design with five replications. Plots were dripirrigated weekly as necessary using a drip tape irrigation system. Fertility and insecticide treatments were applied according to University of Georgia Extension recommendations. Fungicide treatments were applied using a Lee SprayTrac highboy plot sprayer calibrated to deliver 40 GPA at 62 psi through TX-18 hollow cone nozzles. Weather conditions during the trial were relatively dry with no rainfall (July to September) and average high and low temperatures of 85° and 70° F, respectively. Natural inoculum was relied upon. Foliar spray applications were made on 7-day intervals: 12, 19, 27 Jul and 2, 9, 16 Aug. Drip applications were made on 3 Jul (at plant) and 4 Aug (30 days after transplanting). Disease severity was assessed on 24, 31 Jul and 15, 23Aug as percent leaf area with necrosis per plot. Data were analyzed in the software ARM (Gylling Data Management, Brookings, SD) using analysis of variance (ANOV) and the Waller-Duncan test to separate means.