| Abstract/Contents: | "The effect of pasture herbicides on newly established bermudagrass [Cynadon dactylon (L.) Pers.] is not well documented. Field trials were conducted near Stephenville, TX and Marianna, FL in 2002 to determine the effect of various herbicides on newly established bermudagrass. A randomized complete block design with a split, split-plot treatment arrangement was utilized with three replications. The main plots consisted of 'Coastal' and 'Tifton 85'bermudagrass. The sub-plot treatment consisted of four application timings (1,14, 28, and 42 days after planting (DAP). Herbicide treatments were applied using a CO2 backpack sprayer delivering 15 gallons per acre. Herbicide treatments evaluated included Pasturegard (2 pt), LAF-004 (2 pt), Redeem R+P (2 and 3 pt), Envoke (0.5 oz), Cimarron Max (0.5 oz + 2 pt), Fuego (0.56 oz + 12.5 fl oz), Plateau (1,2, and 3 fl.oz.), 2,4-D amine (4 pt), 2,4-D LV ester (3 pt), and Weedmaster (3 pt). Percent visual injury, stolon length, percent crabgrass (Digitaria sp) control was recorded 30 DAT, and percent ground cover was estimated 90 DAP. There was no visual injury to bermudagrass sprigs at the four timing applications with any of the above herbicide treatments, except Plateau. The rates of 1, 2, and 3 oz/A Plateau injured Tifton 85 by 12, 23, and 32%, respectively. The timing applications of 0, 14, 28, and 42 DAP averaged 19, 33, 17, and 19% Tifton 85 injury, respectively. The rates of 1, 2, and 3 oz/A Plateau injured Coastal by 6, 15, and 28%, respectively. The timing applications of 0, 14, 28, and 42 DAP averaged 16, 20, 16, and 13% Coastal injury, respectively. Stolon length was not different regardless of variety or timing; however, there were differences in percent ground cover, due to weed efficacy of the various herbicides. The best timing application for all the plant growth regulating (PGR) herbicides was 1 DAP. This pre-emergent application to crabgrass provided >70% control, which gave an average of 25% groundcover with Tifton 85 and 30% groundcover with Coastal compared to 5% groundcover in the untreated control. However there was no suppression of crabgrass with the PGR herbicides post-emergence and the percent groundcover did not differ from the control. The best timing for 1,2, and 3 oz/A Plateau was 14 DAP, which gave 37, 38, and 52% groundcover for Tifton 85, respectively, and 22, 30, and 35% groundcover for Coastal compared to 5% groundcover in the untreated control. The timing applications (0, 14, 28, and 42 DAP) averaged 32, 42, 28, and 11 % cover for Tifton 85, respectively, and 24, 29, 25, 17% groundcover for Coastal. In summary, the herbicides in this study were relatively safe on newly established bermudagrass, and should be considered for labeling." |
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