Evaluation of fungicides for control of three foliar diseases on creeping bentgrass 2013

摘要

Fungicides were evaluated for the control of dollar spot and a natural infestation of brown patch on a 'Penncross' creeping bentgrass green at the University of Missouri Turfgrass Research Facility in Columbia, MO. The root zone consisted of a 12-in.sand cap over a subgrade with drains. 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 9 Sep, respectively. Nitrogen was first applied using Signature (13-2-13) on 15 and 22 Apr at 0.20 lb N/1000sq ft. From 23 May to 3 Sep, UMaxx (47-0-0) at 0.25 lb N/1000 sq ft + Knife Plus (12-00) or Ferromec (10-2-4) + micros (0.01 lb N/1000 sq ft) was applied every two to three weeks. Revolution (6.0 fl oz/1000 sq ft) was applied every 28 days starting on 8May. Plots were 5 ft x 5 ft and arranged in a randomized complete block 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 nozzles. On 8 May, preventive fungicideapplications were applied on 14, 21, or 28 day intervals through 28 Aug. On 13 May, rye grain (Secale cereale L.) infested with three isolates of Sclerotinia homoeocarpa was uniformly applied at a volume of 1.52-in. per plot using a small broadcast spreader. Inoculum was left on the turf surface for 2 days to enable pathogen establishment. Disease severity and turfgrass quality were assessed every 14 days from initial symptom development. Select rating dates are presented in the tables below to demonstrate disease progress and turfgrass quality in untreated control plots. Disease severity and incidence were assessed as visual estimates of the percent symptomatic area and number of dollar spot infection centers per plot, respectively. Turfgrass qualitywas evaluated using a 1 to 9 scale (9=best, 5=acceptable) based on color, density, and uniformity. Data were subjected to analysis of variance and means separation using Fisher's Protected LSD at (P = 0.05).