| Abstract/Contents: | "DMI fungicides were applied to a 'Tifeagle' bermudagrass putting green on a 14-day interval during the summer to determine their impact on turf health. This trial was conducted at the Lake Wheeler Turfgrass Field Laboratory in Raleigh, NC. Mowing was performed five times weekly at heights of 0.130-in. (prior to 20 Jun), 0.160-in. (20 Jun to 29 Jul), and 0.190-in. (after 29 Jul) with clippings collected. The site was irrigated as needed to prevent drought stress. Fertilizer was applied as 18-3-6 on 18 Apr and 29 May (0.25 lb nitrogen (N)/1,000 sq ft), 13-0-46 on 7 and 22 May (0.43 lb N/1,000 sq ft), 30-0-0 on 18 Jun, 8 Jul, 31 Jul (1.0, 1.25, 0.6 lb N/1,000 sq ft, respectively), and 0-0-25 on 18 Jun, 8 Jul, 31 Jul (1.0, 1.0, 0.7 lb K/1,000 sq ft, respectively). Micronutrients were applied a Multigreen II (3.0 fl oz/1,000 sq ft) on 15 Jul and 8 Aug. Wetting agents were applied on 23 Apr (Cascade Plus, 8.0 fl oz/1,000 sq ft), 4 Jun (Cascade Plus + Duplex, 4.0 fl oz + 1.0 fl oz/1,000 sq ft), and 14 Jul (Cascade Plus + Duplex, 4.0 fl oz + 1.0 fl oz/1,000 sq ft). Plots were 3.33 ft x 6 ft and were arranged in a randomized complete block with four replications. Fungicides were applied in water equivalent to 2 gal per 1,000 sq ft with a CO2-powered sprayer at 40 psi using a TeeJet 9508E nozzle. All treatments were initiated on 16 Jun and reapplied at the appropriate intervals as indicated in the table. Turfgrass quality was evaluated on 24 Jul, 11 and 22 Aug, and 10 Sep, using a 1 to 9 scale (9=best, 5=acceptable) based on color, density, and uniformity. Phytotoxicity was assessed on 24 Jul, 11 and 22 Aug, and 5 Sep using a 0 to 5 scale where 0=no necrosis, and 5=total plot necrosis. Data were subjected to analysis of variance and means separation by Waller-Duncan k-ratio t test (k=100). With the exception of the 22 Aug rating date, turf quality in untreated plots was below the acceptable level. The rotation of Trinity and Fore increased turf quality dramatically after the first application on 24 Jul and also increased turf quality on 22 Aug and 10 Sep. On the other hand, the 2 fl oz rate of Trinity significantly reduced turf quality on three dates (24 Jul, 22 Aug, and 10 Sep) and the 1.5 fl oz rate reduced quality on two dates (24 Jul and 22 Aug). The 2 fl oz and 1.5 fl oz rates of Trinity induced severe phytotoxicity on all rating dates. Banner Maxx, Bayleton, Eagle, and the 0.75 fl oz rate of Trinity induced mild phytotoxicity on one or more evaluation date, but the 0.5 fl oz rate of Trinity did not induce significant phytotoxicity at any time. With repeated application at high label rates, Trinity appears to have greater injury potential on 'Tifeagle' bermudagrass as compared to other DMI fungicides. However, this product can be applied at low rates or in rotation with other chemistries without detrimental effects." |
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