| Abstract/Contents: | "Fungicides were evaluated for their ability to control dollar spot (Lanzia and Moellerodiscus spp.) at the Rutgers Turf Research Station in New Brunswick, New Jersey. A 'Pencross' [Penncross] bentgrass experimental green, established September l985 on a Norton loam, was used for this study. Turf was maintained at 0.25 in. cutting height throughout 1988. Nitrogen was applied as 34-0-0 on 2 Mar, 18 May and 9 Jul (0.7 lb, 1.0 lb, 0.75 lb actual N/1000 sq ft, respectively) and 10-6-4 on 15 Apr (0.5 lb actual N/1000 sq ft ). Soil pH was amended to 6.8 with 1500 lb pulverized Dolomitic limestone/A on 8 Dec, 1987. Plots were 3 ft x 9 ft and treatments were arranged in a randomized block design with four replications. Turf was irrigated as needed to avoid water stress. Weeds were prevented with 0.8 pt 2,4-D amine + 0.5 pt Banvel 4S/A + 12 lb Dacthal 75W/A on 19 Oct, 1987 and 1.0 pt 2,4-D amine on 14 Apr, 1988. Fungicides were applied on 18 Jun, 3 Jul, 23 Jul and 13 Aug. Sprays were applied with a CO2 compressed air sprayer, T-jet nozzle 8003 E, adjusted to 30 psi, in water equivalent to 1.9 gal/1000 sq ft. Plots were artificially inoculated on 24 Jul and 3 Aug with a four isolate mixture of the fungi grown on autoclaved oats to supplement natural infection. Treatments were evaluated visually for number of dollar spot lesion centers/plot on 17 Jun, 26 Jun, 2 Jul, 11 Jul, 20 Jul, 24 Jul, 3 Aug, 10 Aug, 16 Aug, 24 Aug, 1 Sep, 9 Sep, 21 Sep and 29 Sep using a modified Horsefall-Barrett log scale. Data was subjected to an ANOVA and Duncan's Multiple Range Test. Natural infection was first observed and confirmed on 6 Jun, however, infection was not uniformily distributed throughout the study area until 12 Jun (six days after plots were artificially inoculated). Almost all fungicide treatments (table1) provided goof curative control of dollar spot by 26 Jun (9 days post application). Only Fungo 50W (1.0/2.0 oz), Rizolex 75W (1.3 oz), Caddy 20LC (1.0 fl oz and both Caddy programs), Apache 50W (2.0 oz), Chipco 26019 50W (1.0 oz), and Rubigan 50W (0.2 oz) failed to check disease development. Cadmium and benzimidazole resistant fungal isolates were confirmed in the laboratory. as disease pressure intensified (24 Jul = check plots averaged 325 lesion centers), only the first 32 entries adequately protected turf in the study. In table 2, RH-3486 50W (all rates), Nustar 20DF (1.5/0.75 oz), SN 596 25DF (alone and in combination with Prochloraz 40%E), SDS-66533 F + Daconil 2787 4F (both combination rates), Daconil 720 6F (8.0 fl oz), FBC 39865 25W (1.0 oz), Banner 1.1E (2.0 fl oz), and Lynx 1.2E (1.7 fl oz) afforded good dollar spot control up to 48 days after the last fungicide application. DPX-965 50DF, Prochloraz 40%E, Apache 50W, and Fungo 50W did not improve the efficacy of tank mix combinations tested. Chipco 26019 2F (2.0 fl oz) provided significantly better dollar spot Protection then the 50W (1.0 fl oz) formulation. Plots treated with Bayleton 25DF (1.0 oz), Banner 1.1E (both rates), SDS-66533 F + Daconil 2787 4F (both treatment combinations) and RH-3486 50W (6.0 oz) were significantly greener than untreated turf, while plots treated with Prochloraz 40%E (4.5 fl oz) were noticeably lighter in color for 3-5 days after each application (based on visual observations)." |
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