Evaluation of multiple fungicides for summer disease control on greens height creeping bentgrass, 2014

摘要

Fungicides were evaluated for disease control at the University of Missouri Turfgrass Research Facility in Columbia, MO on a 'Penncross' creeping bentgrass green. The green contained a 12-in sand root zone over a drained subgrade. Mowing was performedat 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 at 0.39 lb N/1000 sq ft thereafter from 16 May to 29 Aug. Revolution~R (6.0 fl oz/1000 sq ft) was applied every 28-d starting on 16 May. 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. Preventative fungicide applications were applied on 14 d intervals from 8 May - 31 Jul. On 23 May, rye grain (Secale cereale L.) infested with the dollar spot pathogen was uniformly applied at a volume of 1.52-in.3 per plot using a small broadcast spreader and left on the turf surface for 3 days before mowing. 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 9scale 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 (P=0.05). To stabilize variance, disease severity and turf quality datawere square-root transformed for analysis and back-transformed for presentation.