Control of brown patch of tall fescue using fungicides and biofungicides, 2007

摘要

A fungicide trial was conducted on a 5-year-old sward of tall fescue cv. ‘Kentucky 31’ grown on a clay loam soil (pH 5.8) at the Georgia Experiment Station, Griffin, GA. Fertilizer treatments consisted on 1.0 lb nitrogen (Lesco 24-4-10) per 1000 sqft applied on 7 Jun and 6 Jul. The turfgrass was maintained at a height of 3- in. by mowing once a week. Turfgrass cultural practices were similar to those prescribed for maintenance of tallfescue lawns in Georgia. Treatments were arranged as plots (5 ft x 5 ft) in a randomized complete block design with four replications. Initial applications were made on 26 Jun 07 in 2.0 gal water per 1000 sq ft with a hand held, CO2-pressured boom sprayer at 30 psi using XR TeeJet 8002vs nozzles. Subsequent applications were made at 14 day intervals. Rhizoctonia solani inoculum was obtained by growing the fungus in a wheat-barley-oatsmixture, which was soaked in water overnight and then double sterilized in an Erlenmeyer flask. Turf was inoculated 24 hours after the initial fungicide applications by hand-dispersal of grain infested with R. solani intothe foliar canopy. The plots received approximately 0.1-in. of irrigation water 3 times daily (11:00 AM; 3:00 PM and 7:00 PM) for 3 weeks to ensure nightly foliar wetness for infection. Hot and dry conditions observed duringthe experiment required us to implement this irrigation schedule. Normal irrigation was received at 3:00 AM after the first 21-days. Visual estimates of disease severity were made using the Horsfall-Barratt rating scale. Data wastransformed to percent of disease. For each evaluation date, disease severity was analyzed by ANOVA (alpha =0.05) and means were statistically separated using Fisher’s Protected LSD at a probability value of alpha = 0.05.