| Abstract/Contents: | "Control of brown patch with chemical and biological fungicides, 1997: Fungicides were evaluated for their ability to control brown patch at the Rutgers Turf Research Farm in North Brunswick, NJ on colonial bentgrass maintained under golf course fairway conditions. The turf was established Sep 1995 on a Norton loam with a pH of 6.1. Mowing was performed three times weekly at a height of 0.4 in. with clippings collected, and the site was irrigated to prevent drought stress. Fertilizer was applied as 20-0-20 on 23 May (0.5 lb N/1000 sq ft), 46-0-0 on 20 Jun (0.5 lb N/1000 sq ft), 15-0-0 on 31 Jul (0.5 lb N/1000 sq ft), and 46-0-0 on 5 Aug (0.8 lb N/1000 sq ft). Weeds were controlled with Betasan 4-E (7 fl oz/1000 sq ft) on 28 Apr and MCPP-4 amine (1fl oz/1000sq ft) plus Banvel (0.18 fl oz/1000 sq ft) on 10 Jul. Insect pest were suppressed with Turcam (1 oz/ 1000 sq ft) on 17 Jun and Dursban (2 fl oz/1000 sq ft) on 1 Aug. Aquaduct wetting agent (8 fl oz/1000 sq ft) was applied on 9 Jun, 24 Jun, 1 Jul, 8 Jul, and 27 Jul to control localized dry spots. Hollow tine aerification was performed on 7 Jul with 0.375 in. tines on 2 in. centers. Plots were 3 ft x 9 ft and were arranged in a randomized complete block with four replications. Fungicides were applied in water equivalent to 2 gal per 1000 sq ft with a CO₂ powered sprayer at 30 psi using TeeJet 8003E nozzles. Treatments (trt) 1, 2, 3A, 4A, 5A, and 6A appropriate intervals as indicated in the table. Percent turf area infected with R. solani was assessed on 13 Jul (data not shown), 27 Jul, 29 Jul, 14 Aug, 20 Aug, and 3 Sep. Data were subjected to analysis of variance and means separation by Waller-Duncan k-ratio t test (k=100) following arcsine transformation. Brown patch infections was first observed on 13 Jul. Disease pressure was interrmittent in Jul and early Aug, but intensified through Aug and peaked in early Sep. Excellent brown patch control was provided throughout the season with Heritage 50WG (trt 15, 24), Sentinel 40WG (trt 25), Prostar 50W (trt 40, 41), Prostar 50W+Bayleton 50W (trt 42), WAC 71 90WG (trt 37, 38), Cleary 3336 50W (trt 35), Daconil Ultrex 82.5WDG (trt 7), Procymidone 50W (trt 11, 12), S-7222 WG= S-7221 W (trt 32, 33), S-7225 W+ S-7221 W (trt 30, 31), and the high rates of RRU041523S (trt 22, 23), RU200112W (trt 14), IB 10351 WG (trt 17), and AE B066752 (trt 58). Extended residual control was observed on 3 Sep for many treatments, including Heritage 50WG (trt 15, 24), Senntinel 40WG (trt 25), Prostar 50W (trt 40, 41), Prostar 50W + Bayleton 50W (trt 42), WAC 71 90WG (trt 38), RU041523S (trt 22, 23), S7225 W+ S-7221 W (trt 30, 31), S-7222 WG + S-7221 W (trt 32, 33). Companion I and Companion II (Bacillus subtilis) provided little control of brown patch when applied alone (trt 1, 2); however, the addition of Companion II to the 3.8 oz rate of Daconil Ultrex 82.5WDG (trt 5) enhanced disease control on 29 Jul and 3 Sep compared to either fungicide alon. A single application of Heritage 50 WG (trt 10) was more effective and lasted longer than a single application of Sentinel 40WG (trt 9) applied on the same date, but the fungicides were equally effective when applied on 21 day intervals (trt 24, 25). Combining Eagle 40W with Heritage 50WG (trt 44) did not extend or enhance disease control afforded by Herritage 50WG alone (trt 15). Treatments containing Prostar 50W alone (trt 40, 41) or in combination with Bayleton 50W (trt 42) provided similar levels of desease suppression throughout the season. Continued application of Sentinel 40WG (trt 25), Prostar 50W (trt 40, 41),Prostar 50W + Bayleton 50W (trt 42), Heritage 50WG (trt 15, 24), and S-7225 W + S-7221 W (trt 30, 31) resulted in improved disease control and extended residual efficacy, even though disease pressure intensified throughout the study. Under high disease pressure late in the season, CGA-371367 (Pseudomonas fluorescens, trt 48) provided some disease suppression compared to untreated turf. When combined with fungicide applications (trt 52, 53, 54), CGA-371367 did not enhance disease control compared to the fungicides alone (trt 49, 50, 51). Phytotoxicity was observed as foliar necrosis on 14 Aug and 20 Aug for plots treated with the 5.04 fl oz rate of RU041523S (trt 23). Slight reductions in stand density were observed on 15 Sep for all plots treated with triazole fungicides (data not shown)." |
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