Evaluating Briskway for dollar spot and brown patch control on greens height creeping bentgrass, 2014

摘要

Briskway applications were evaluated for disease control and potential phytotoxicity at the University of Missouri Turfgrass Research Facility in Columbia, MO on a 'Penncross' creeping bentgrass naturally infested with Sclerotinia homoeocarpa. The green contained a 12-in sand root zone over a drained subgrade. Mowing was performed at a height of 0.13-in., three and five times weekly from 2 Apr to 7 Jun and 7 Jun to 19 Sep, respectively. Nitrogen was applied at 0.20 lb N/1000 sq ft on 18 Apr. and every 3 wks thereafter at 0.39 lb N/1000 sq ft from 16 May to 29 Aug. Revolution (6.0 fl oz/1000 sq ft) was applied every 28-d starting on 16 May. Three applications of Daconil Ultrex (3.25 oz/1000 sq ft) were applied on 14-d intervals from 7 May - 3 Jun across the entire trial area to prevent disease occurrence before trial initiation. On 17 Jun, an additional Daconil Ultrex (3.25 oz/1000 sq ft) was made only to plots slated to receive 0.725 and 1.45 fl oz/1000 sq ft of Briskway to prevent disease occurrence before initial applications were made on 1 Jul. Plots were 5 x 5 ft and arranged in a randomized complete block design with four replications. Treatments were applied in water equivalent to 2 gal/1000 sq ft with a CO2-powered sprayer at 26 psi using TeeJet 8008 flat fan nozzles. Briskway treatments were applied from 17 Jun - 15 Jul, three times at 0.5 or 1.0 fl oz oz/1000 sq ft, or twice at 0.725 or 1.45 fl oz/1000 sq ft on a 14 d interval. These treatments represent low and high rates of Briskway, and a potential high rate spray overlap. Disease severity and turfgrass quality were assessed every 14-d from initial symptom development. Brown patch was assessed as a visual estimate of the percent symptomatic area and dollar spot was quantified as counts of infection centers per plot. Turfgrass quality was evaluated using a 1 to 9 scale (9=best, 5=acceptable) based on color, density, and uniformity. Phytotoxicity was evaluated using a 0 to 9 scale with 0 = none, > 2 = unacceptable discoloration, and 9= total plot necrosis. Data were subjected to analysis of variance and means separation using Fisher's Protected LSD test (i>=0.05).