Fungicide program for dollar spot and brown patch management of creeping bentgrass in Georgia, 2008

摘要

A fungicide trial was conducted on a 15-yr-old sward of creeping bentgrass grown on a sand/peat root zone (pH 6.2) at the Georgia Experiment Station. Fertilizer treatments consisted of 1.0 lb and 0.5 lb nitrogen (Lesco 24-4-10) per 1,000 sqft applied on 5 May and 8 Sep, respectively. The turfgrass was maintained at a height of 0.2-in. by mowing three times per week. The objective of the trial was to establish a management program that provides disease control and high turf qualitythroughout the bentgrass management year with a rotation of fungicides. Emphasis was placed on dollar spot and brown patch. Treatments were arranged as plots (3.3 ft X 5 ft) in a randomized complete block design with four replications. Aninitial application was made on 20 May and followed by additional fungicide applications at a 14-day interval. Fungicides were applied using 2.5 gal of water per 1,000 sq ft with a wheel-mounted, CO2-pressured boom sprayer at 30 psi using XRTeeJet 8002VS nozzles. On 21 May, the experimental plots were inoculated with a bentgrass isolate of S. homoeocarpa. On 26 Jun experimental plots were inoculated with a bentgrass isolate of R. solani grown on a tall fescue/barley/wheat seedmixture. The plots received approximately 0.24 in. of irrigation water daily at 15:00 and 17:00 hr to ensure foliar wetness for infection. Visual ratings were performed at 7- to 14-day intervals from the initial application date. For dollar spot, infectioncenters were counted while visual estimates of brown patch disease severity were made using a modified 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.