| Abstract/Contents: | "Fungicides were evaluated for their effect on the summer quality of creeping bentgrass putting greens. This trial was conducted at the Sandhills Research Station in Jackson Springs, NC on 'L-93' creeping bentgrass maintained under putting green conditions. Mowing was performed five times weekly at a height of 0.156-in. with clippings collected, and the site was irrigated to prevent drought stress. Fertilizer was applied as 18-3-16 on 13 Jan, 20 Mar, and 25 Apr (0.94 lb N/1000 sq ft respectively); and 28-8-18 on 23 May, 12 and 19 Jun, 11 Jul, and 1 and 23 Aug (0.125 lb N/1000 sq ft respectively). Insect pests were suppressed with DeltaGard GC (0.6 fl oz/1000 sq ft) on 23 May and 21 Jul, and Sevin SL (3.0 fl oz/1000 sq ft) on 1 Aug. Harrell's CalMax (0.1 lb Ca/1000 sq ft) was applied on 4 Apr, 23 May, 12 Jun, and 24 Jul; and Harrell's Minormax (4.0 fl oz/1000 sq ft) was applied on 19 Jun and 11 Jul. Weed control was applied as Andersons Goosegrass/Crabgrass Control (2.62 lb/1000 sq ft) and Trimec Bentgrass Formula (1.0 fl oz/1000 sq ft) on 23 Mar and 4 Apr respectively. Magnus wetting agent (4.0 fl oz/1000 sq ft) was applied on 6 and 19 Jun, 11 and 21 Jul, and 1 Aug. 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 1000 sq ft with a CO2-powered sprayer at 40 psi using TeeJet 8004 nozzles. All treatments were initiated on 9 Jun, unless otherwise noted in the table. Fungicides were reapplied at the appropriate intervals as indicated in the table. Percent turf area exhibiting brown patch symptoms was assessed on 23 Jun, 18 Aug, and 6 Sep. Percent turf area exhibiting anthracnose symptoms was evaluated on 18 Aug. Turfgrass quality was evaluated on 23 Jun, 7 and 21 Jul, and 4 and 18 Aug, using a 1 to 9 scale (9=best, 5=acceptable) based on color, density, and uniformity. Multispectral radiometry was also used to assess turfgrass quality on 18 Aug using a CropScan MSR16R radiometer. Data were subjected to analysis of variance and means separation by Waller-Duncan k-ratio t test (k=100). Turfgrass quality fluctuated during summer 2006, declining during periods of persistent hot weather in mid July and early August. High and low temperatures were consistently greater than 90°F and 70°F, respectively, during these periods. Few treatments provided consistent improvements in turfgrass quality throughout the course of the summer. Only Signature + Daconil Ultrex and the Daconil Program significantly increased turfgrass quality on 7 Jul, 21 Jul, 4 Aug, and 18 Aug. Applications of Daconil Ultrex, Endorse + Protect alternated with CL-EXP-11 + Protect, and QP Chlorothalonil + Signature significantly increased turf quality on 3 of these 4 rating dates. Symptoms of brown patch were noted in the trial area periodically during the season, and the appearance of this disease had a significant impact on turfgrass quality. On 23 Jun, most treatments provided good suppression of brown patch, except the two rates each of Signature and PEX 6012, PEX 6013 (4 oz), Signature + Fore, Fore, and Tartan (1 fl oz), which provided no significant control. In general, treatments that provided good brown patch suppression exhibited improved turfgrass quality on 7 Jul. A more severe epidemic of brown patch was observed on 6 Sep, 33 days after the final application of each treatment. On this date, Heritage TL, Rhapsody + Heritage TL, Tartan (1.5 and 2.0 fl oz [14 and 28-day intervals]), Tartan + Signature, Endorse + Protect alternated with CL-EXP-11 + Protect, 3336 Plus + CL-EXP-11 + Protect, Quali-Pro Iprodione + Signature, 26GT + Signature, Daconil Program, and Fore Program continued to provide excellent brown patch suppression. Applications of Rhapsody Biofungicide provided a significant reduction in brown patch incidence on 23 Jun, but did not affect brown patch or turfgrass quality on other rating dates. No significant differences in anthracnose incidence were detected on 18 Aug. Multispectral radiometry data, collected on 18 Aug, concurred with visual quality ratings collected on the same date, with plots exhibiting increased visual quality being characterized by higher LAI and lower Stress 1 and Stress 2 values." |
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