| Abstract/Contents: | "Fungicides were evaluated for their ability to control dollar spot at the Rutgers Turf Research Farm in North Brunswick, NJ on creeping bentgrass maintained under golf course fairway conditions. Turf was established Sep 1996 on a Norton loam with a pH of 6.5. Mowing was performed three times weekly at a height of 0.4 in. with clippings collected. The site was irrigated as needed to prevent drought stress. Fertilizer was applied as 20-0-20 on 16 Apr (0.5 lb. N/1000 sq ft), 46-0-0 on 20 Jun (0.5 lb. N/1000 sq ft), 16-4-8 on 4 Aug (0.5 lb. N/1000 sq ft), and 20-0-20 1 Oct (0.5 lb./1000 sq ft). On 15 Apr, turf was aerified with 0.5 in. hollow tines on 4 in. centers. Insects were controlled with Turcam 76W (7.35 fl oz/1000 sq ft) on 17 Jun and on 27 Apr with Betasan 4E (7.35 fl oz/1000 sq ft). Plots were 3 ft x 9 ft and were arranged in a randomized complete block with four replications. Fungicides were applied in water equivalent to 1.9 gal per 1000 sq ft with a CO₂ compressed air sprayer at 30 psi using TeeJet 8003 nozzles, except for trt 95, 97A, 98A, and 99A which were applied in 9.5 gal water/1000 sq ft. Treatments were initiated on 24 Jun when environmental conditions were conducive to dollar spot development. Fungicides were reapplied at the appropriate intervals as indicated in the table. The test area was inoculated with infested bentgrass clippings on 22 Jul, 5 Aug and 19 Aug to supplement natural infection. Turf was visually evaluated for number of dollar spot infection centers per plot on 9 Jul and 25 Jul (data not shown), 8 Aug, 18 Aug, 28 Aug, 11 Sep and 26 Sep. Data were subjected to analysis of variance and means separation by Waller-Duncan k-ratio t test (k=100). Dollar spot was not observed until 9 Jul. Symptom expression was minimal until mid-Aug when the disease intensified rapidly. Disease activity peaked in early Sep. All treatments provided acceptable control of dollar spot through 28 Aug except Lynx 25 DF + Heritage 50 WG (trt 24), RU200112 W (trt 29, 30), the 0.37 oz rate of IB 10351 WG (trt 31), Clearly 3336 4.5F (trt 57), RU181603B (trt 61, 62), Heritage 50WG (trt 63), Daconil Ultrex 82.5SDG alternated with Heritage 50 WG (trt 64), UBI 1716B (trt 82, 83), UBI 1716B + Heritage 50WG (trt 86), UBI 1716B + UBI 4087 (trt 88), UBI 1876 (trt 89), UBI 4087 (trt 90), QST 177 (trt 94), and Pseudomonas aureofaciens TX-1 (trt 95). Good to excellent residual control (30 to 48 days post-treatment) was observed on 11 Sep for the turf treated with Banner Maxx 1.24 MC + Daconil 2787 Zn 4F (trt 4), Sentinel 40 WG (trt 5), Sentinel 40WG + Daconil 2787Zn 4F (trt 8), CGA-BMP 46.5W (trt 13, 15), CGA-173506 50W + Banner Maxx 1.24MC (trt 17), Bayleton 25 DF (trt 18), Bayleton 25DF + Daconil Ultrex 82.5SDG (trt 19), Procymidone 50W (trt 27, 28), RU041523S + Atplus 435 (trt 37, 38, 39), S-7286 G (trt 79) and Eagle 40W (trt 92, 93). By 26 Sep, CGA-BMP 46.5W (trt 13), Promcymidone 50W (trt 27, 28), RU041523S (trt 37-39), S-7286 G (trt 79), and Eagle 40W (trt 92, 93) still provided acceptable disease control 45 to 63 days post-treatment. On that date, CGA-BMP 46.5W applied at 0.5 oz every 7 days (trt 13) was superior to the 1.0 oz rate applied on a 14 day schedule (trt 15). All curative treatments (trt 65-75) provided almost complete suppression of dollar spot by 18 Aug (12 days post-treatment). The incidence of dollar spot was enhanced on most rating dates by Heritage 50WG (trt 63) and RU181603B (trt 61, 62). Tank mixing other fungicides such as Banner Maxx 1.24MC (trt 3), Sentinel 40WG (trt 7), and Bayleton 25DF (trt 20), with Heritage 50WG provided excellent control of dollar spot through 28 Aug (22 days post-treatment). No phytotoxicity was observed." |
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