| Abstract/Contents: | "Twenty-six chemical treatments were evaluated on a 14-year-old sward of creeping bentgrass at the Cambridge Research Station, University of Guelph, during June, July and August, 1991. The fungicides tested included: Daconil 2787F, Rovral Green, Thiram 80WP, Tersan 1991 WP50, and Dyrene 50WP, which are registered and recommended for use to control dollar spot disease of turfgrass in Ontario. Twenty other treatments were also tested. Inocula of five isolates grown on autoclaved chicken scratch were dried, ground up and applied at the rate of 1 g/m2 on 21 June. Fungicides were applied to 1 m x 2 m plots with a wheel-mounted compressed air boom sprayer at 140 kPa. Treatments were arranged in a randomized complete block design with 4 replications. Application of 14-day interval treatments were made on 19 June, 3 July, 17, July, 31 July, and 14 August. Application of 21-day interval treatments were made on 19 June, 10 July, and 31 July. Weekly disease ratings were made between 19 June and 11 September. The final observations were made wither 4 or 6 weeks after the last fungicide applications to examine residual effects. The following chemicals gave excellent control of dollar spot disease and showed efficacy longer than their recommended spray intervals: Rovral Green, Tersan 1991, ASC6679l1 at two rates, ASC66825 at 24 or 48 g/100m2, Daconil 2787 at 192 mL/100m2, Banner 130EC at two rates, Banner 1.8% G at 419 g/100m2, and Nova at 30 g/100m2. Chemicals with very good control during the application periods, but had shorter, yet acceptable periods of residual activity were: ASC66518 at 110 g/100m2 and Nustar at 5 g/100m2. Chemicals with borderline efficacy results were: Dyrene 50WP, ASC66825 at 12 g/100m2, Daconil WDG at 106 g/100m2, and Nova at 15 g/100m2. Chemicals showing little or no control of dollar spot disease were: Thiram 80WP, Daconil 2787 at 96 mL/100m2, Daconil WDG at 53 g/100m2, Banner 1.8%G at 224 g/100m2, Captan 80WP, Captan + Nustar, and Fore. No phytotoxicity was observed." |
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