Seeded bermudagrass response to herbicides during ... - GCSAA

Although injury to bermudagrass fromthese herbicides is physiologically interestingbecause these herbicides are primarily activeon dicotyledonous broadleaf plants, suchinjury has been reported previously for establishedbermudagrass turf. Repeat applicationsof Confront have been reported to causeinjury levels of 30%-40% to common, Tifwayhybrid and Tifeagle hybrid bermudagrasses(6). Bermudagrass injury from products containingtriclopyr is so significant that triclopyris often used in spray mixes with fenoxapropor fluazifop for selective removal of bermudagrassfrom tall fescue (Festuca arundinacea) andRESEARCHzoysiagrass (Zoysia species) (3).Similar trends were observed for theeffect of herbicides for broadleaf weed controlon common bermudagrass cultivar groundcover (Table 2). The low and high rates ofConfront reduced ground cover compared tothe nontreated plots for all cultivars 21 days% GROUND COVER VS. HERBICIDESPrincess 77 Riviera Savannah YukonDays after intial treatment21 42 21 42 21 42 21 42Rate Application timingHerbicide (metric units) (DAIT)% cultivar ground cover*AAtrex 2.0 quarts/acre 0 24 d 79 c 29 d 88 abc 26 d 75 b 4 f 25 e(4.7 liters/hectare)Millennium Ultra (low) 1.25 pints/acre 0 68 ab 84 b 80 a 92 abc 82 a 97 a 29 d 59 cd(1.5 liters/hectare)Millennium Ultra (high) 2.5 pints/acre 0 68 ab 85 b 65 bc 87 bc 81 a 95 ab 29 d 61 bcd(2.9 liters/hectare)Trimec Classic (low) 1.75 pints/acre 0 76 ab 89 ab 68 bc 85 c 83 a 97 a 41 c 62 bcd(2.0 liters/hectare)Trimec Classic (high) 3.5 pints/acre 0 63 bc 91 ab 71 bc 89 abc 80 a 97 a 31 d 64 bc(4.1 liters/hectare)Revolver 17.4 fl oz/acre 0 82 ab 94 ab 84 a 97 ab 84 a 95 ab 48 ab 76 a(1.3 liters/hectare)MSMA (low) 1.35 fb 1.35 pints/acre 0 fb 7 71 ab 99 a 82 c 99 a 82 c 97 a 53 a 81 a(1.6 fb 1.6 liters/hectare)MSMA (mid) 2.0 fb 2.0 pints/acre 0 fb 7 80 ab 99 a 82 a 98 ab 82 a 97 a 39 c 81 a(2.3 fb 2.3 liters/hectare)MSMA (high) 2.65 fb 2.65 pints/acre 0 fb 7 78 ab 99 a 79 ab 99 a 80 a 93 ab 43 b 80 a(3.1 fb 3.1 liters/hectare)Drive 1.0 lb/acre(1.1 kilograms/hectare) 0 79 ab 100 a 72 b 99 a 84 a 97 a 25 d 71 ab+ 1.5 pints/acre(1.8 liters/hectare) of MSOConfront (low) 1.0 pints/acre 0 51 c 89 ab 69 bc 94 abc 66 b 92 ab 16 e 55 c(1.2 liters/hectare)Confront (high) 2.0 pints/acre 0 43 c 91 ab 66 bc 88 abc 41 c 86 ab 11 ef 51 d(2.3 liters/hectare)Monument 0.47 ounces/acre 0 75 ab 97 ab 62 c 95 abc 83 a 93 ab 29 d 63 b(32.9 grams/hectare)+ 0.25% v/v NISNot treated — — 81 ab 91 ab 82 a 97 ab 83 a 97 a 55 a 71 ab*Different letters within the same column indicate significant differences in % ground cover among treatments for the same cultivar.Note. Treatments applied from four to seven weeks after emergence at the onset of uniform stolon development. Percent bermudagrass ground cover rated on ascale of 0 to 100, where 0 equals bare ground and 100 equals no exposed soil. Abbreviations: DAIT, days after initial treatment; fb, followed by; MSO, methylated seedoil surfactant; NIS, non-ionic surfactant.Table 2. Percent green turf coverage by the seeded bermuagrass cultivars 21 and 42 days after initial treatment (DAIT) applied four to seven weeks after seedlingemergence when cultivars begin stolon development.January 2005GCM 157