Evaluation of fungicides for control of watermelon anthracnose, 2006

摘要

The experiment was conducted at the Oklahoma State University Research Station in Perkins, OK in a field of Vanoss silt loam previously cropped to peanuts. Granular fertilizer (56-20-62 lb/A N-P-K) was incorporated into the soilprior to direct seeding on 14 Jun. Dual II Magnum 7.6E at 1 pt/A and Sandia 75WG at 0.75oz/A were broadcast immediately after planting for weed control. The experimental design was a randomized complete block with four blocks separated by a 10-ft fallowbuffer. Plots consisted of single, 21-ft-long rows spaced 15 ft apart. Plants were thinned to achieve a within-row spacing of ca. 2 ft. Plots were top-dressed with granular fertilizer (46-0-0 lb/A N-P-K) on 25 Jul. Squash bugs were controlled with Ambush2E at 12.8 oz/A on 1 Aug and 15 Aug. Fungicides were applied broadcast through 8002vk flat-fannozzles spaced 18 in. apart with a CO2-pressurized wheelbarrow sprayer. The sprayer was calibrated to deliver 24 gal/A at 40 psi. Treatments were applied on 7-day intervals beginning 24 Jul. Plots were inoculated with Colletotrichum obiculareon 25 Jul by spreading 1.7 fl oz of colonized oat kernels along the center of each plot. After emergence, plots received sprinkler irrigation to promote plant growth and disease development. Rainfall (in.) during the cropping period (14 Jun to 21Sep) totaled 2.09 for Jun, 2.08 for Jul, 1.71 for Aug, and 2.68 for Sep. Disease incidence (percentage of leaves with symptoms that included defoliation) and defoliation (percentage of leaves defoliated) were estimated in three areas per ploton 19 Sep. Yield of marketable melons weighing 14 or more lbs was taken on 28 Aug and 21 Sep. Melons were classified as diseased or healthy based on the presence or absence of anthracnose lesions.