Efficacy of fungicides for control of pythium blight on tall fescue, 2008.

摘要

A fungicide trial was conducted on a 7-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 of 1.0 lb nitrogen (Lesco 24-4-10) per 1,000 sqft applied on 9 Jun and 7 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 tall fescue 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 applied on 2 Jul 08. Treatments were sprayed in 2.5 gal water per 1,000 sq ft with a hand held, CO2-pressured boom sprayer at 30 psi using XR TeeJet 800 2vsnozzles. Subsequent applications were made at 14 days depending on the treatment. A total of 5 applications were made.Pythium aphanidermatum inoculum was obtained by growing the fungus in a wheat-barley-oats mixture, which was soaked in water overnight and then double sterilized in an Erlenmeyer flask. Turf was inoculated 24 hr after the initial fungicide applications by hand-dispersal of grain infested with P. aphanidermatum into the turf canopy. The plots received approximately 0.1 in. of irrigation water daily 3 times a day (11:00 AM; 3:00 PM and 7:00PM) for 3 weeks to ensure nightly foliar wetness for infection for 3 weeks. Normal irrigation was resumed daily at 3:00 AM after the first 21 days. Two applications of flutalonil (Prostar at 2.0 oz/1,000 sq ft) were made at 21-day intervals to avoid infections of Rhizoctonia solani. Visual estimates of disease severity were made using a modified version of the Horsfall-Barratt rating scale. Values were subjected to analysis of variance and means were statistically separated using Fisher’s protected LDS at alpha=0.05