| Abstract/Contents: | "Several experimental and newly registered fungicides were examined at the Rutgers Turf Research Station in New Brunswick, N.J. for their ability to control brown patch (Rhizoctonia solani). Turf, consisting of 'Penncross' bentgrass, was established Sep 1985 on a Norton loam and maintained at 0.5 in cutting height throughout the 1987 growing season. Nitrogen was applied as 10-6-4 on Apr (1.0 lb actual N/1000 sq ft), 17 Jul (1.0 lb actual N/1000 sq ft) and 31 Jul (0.75 lb actual N/1000 sq ft). Soil pH was amended to 6.4 with 1500 lb pulverized Dolomitic limestone/A on 17 Mar. Weeds were controlled with 1.5 pt 2,4-amine + 0.5 pt Banvel 4S /A on 14 Apr and 14 lb Dacthal 75W /A on 30 Apr. Turf was irrigated as needed to avoid water stress. Plots were 3 ft x 9 ft and treatments were arranged in a randomized block design with four replications. Sprays were applied with a carbon dioxide compressed air sprayer, T-jet nozzle 8003 E, adjusted to 30 psi, in a water equivalent of 1.9 gal/1000 sq ft. Fungicides were applied on 27 Jun, 10 24 Jul, 6 and 20 Aug, except for Dyrene 4F (8.0 fl oz) which was only applied as a curative treatment on 6 and 20 Aug. Plots were artificially inoculated on 30 Jul with a five isolate mixture of R. Solani (grown on autoclaved oats) to supplement natural infection. Treatments were visually evaluated for percent turf area infected with Rhizoctonia brown patch on 9 Aug and 28 Aug using a modified Horsefall-Barrett log scale. Data was subjected to an arc-sin transformation prior to statistical analysis. A table showing the different treatments and rates and turf area infected (percentage) on the dates of 9 Aug and 28 Aug is included. Brown patch, stimulated by the application of Rhizoctonia-infected oats, developed rapidly after 4 Aug. By 6 Aug, infection was severe (up to 53% of untreated turf exhibiting disease symptoms) and uniformly distributed throughout the test area. Although inoculum pressure was intense during the peak summer infection period (6-28 Aug), Systhane 40W (all three rates), Bay HWG 1608 25W (0.48 and 1.0 oz) Banner 1.1E, RH-7592 0.5E (4.0 and 8.0 fl oz), Bayleton 25DF, Nustar 20DF + DPX-965 50DF, Dyrene 4F (4.0 and 6.0 fl oz), Nustar 20 DF (1.5 oz), Chipco 26019 2F (2.0 and 8.0 fl oz) and RH-3486 50W (2.0 and 8.0 oz) provided good to excellent disease control. As the epiphytotic began to subside in late-Aug, all treatments afforded adequate brown patch control except Rizolex 75 WDG (4.3 and 8.5 oz), Chipco 26019 50W (1.0 and 4.0 oz), Tersan 1991 50W (2.0 oz) and Dyrene 4F (8.0 fl oz - curative treatment). The combination of Nustar 20DF + DPX-965 50DF significantly improved disease control when compared to Nustar 20DF (0.75 oz) alone. Phytotoxicity (apparent as a slight foliar tip necrosis) was detected on 9 Aug for all plots receiving RH-7592 0.5E (8.0 fl oz rate). Turf recovered completely within 5-7 days, however, and no further injury was observed. Plots treated eith Nustar 20DF (1.5 oz), Systhane 40W (all three rates) and Banner 1.1E (2.0 fl oz) were noticeably greener than other areas in the study. This conditions was apparent from 6 Aug to 20 Sept." |
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