Evaluation of fungicide programs for the management of dollar spot and brown patch of creeping bentgrass, 2009.

摘要

Plots were established on a putting green at the Turfgrass Research Center located in Stillwater, OK. Plots were 3 ft wide and 5 ft long with 1-ft alleys between plots. The experimental design was a randomized complete block with four replicates. The turfgrass sward was a mature stand of creeping bentgrass established on a USGA sand/peat mix soil. Recommended maintenance and irrigation practices were followed throughout the growing season. Plots were infested with S. homoeocarpa by uniformly spreading wheat grains colonized by the fungus over plots on 24 May. Plots were infested with R. solani by placing two fungus-colonized wheat grains in the center of each plot on 28 Jul. All fungicide programs, except the ADVISORY program, were applied on a 14-day application interval and were initiated on 1 May. Treatments were applied according to regression-based disease prediction models developed for dollar spot (developed at Oklahoma State University) and brown patch (developed at University of Maryland). Additional programs were included from BASF Specialty Products (BASF 1 and BASF 2); one program was included from Cleary Chemical (CLEARY); and two alternative programs (OSU 1 and OSU 2). A non-fungicide treated control was also included. Fungicides were applied with a CO2-pressurized wheelbarrow sprayer equipped with TX8008 flat fan nozzles and calibrated to deliver 87 GPA or 2 gal/1000 sq ft. Ratings of the number of dollar spot foci (rating began 1 May), percent of plot with symptoms of brown patch (rating began 19 Jun), and turfgrass quality (scale of 1 - 9 scale where 1 = no turf present, 5 = unacceptable turfgrass, 6 = acceptable turf, 9 = dense, dark color, thick stand of turfgrass; rating began 1 May) were taken at 7-day intervals. Dollar spot and brown patch disease data were subjected to the area under the disease progress curve (AUDPC) transformation to account for season-long ratings. These data and turf quality data were analyzed using ANOVA (alpha = 0.05). Multiple comparisons of means were performed using Fisher’s test of protected least significant difference (alpha = 0.05).