Efficacy of Postemergence Grass Herbicides on Common Bermudagrass

C.D. Monks, M.G. Patterson, and W.B. Webster


 
ABSTRACT

A preliminary study was conducted in 1986 with five postemergence grass herbicides and two sources of nitrogen on common bermudagrass in cotton. The study was initiated at the Tennessee Valley Substation, Belle Mina, Alabama on a Decatur Silt loam containing 1.5% organic matter. A randomized complete block experimental design with 4 replications was utilized for this study. Poast, Fusilade 2000, Assure, RE-45601, and DPX-Y6202-31 were applied over the top of 1 inch and/or 10 inch common bermudagrass. The two sources of nitrogen were 28% nitrogen solution and ammonium sulfate. Nitrogen was combined with Poast rates of 0.1, 0.2, and 0.3 lb ai/A in an effort to increase herbicidal activity. Visual weed control ratings, crop injury ratings, and cotton yield were recorded to evaluate each herbicide's performance.

Two weeks after initial application, Poast, Fusilade 2000, Assure, RE-45601, an d DPX-Y6202-31 provided fair to good (75-90%) control of common bermudagrass at rates of 0.4, 0.2, 0.125, 0.125, and 0.125 lb ai/A, respectively. These treatments provided similar common bermudagrass control after 10 weeks. RE-45601 and DPX-Y6202-31 applied sequentially at rates of 0.125 and 0.031 lb ai/A provided fair to good season-long control of common bermudagrass. The addition of nitrogen to the spray solution did not increase the activity of Poast. No crop injury occurred due to the application of postemergence grass herbicides.

Seed cotton yields were greatly reduced due to the extremely high population of common bermudagrass. The seed cotton yield for the untreated check was 244 lbs/A. Seed cotton yields of 760, 549, 525, and 561 lbs/A were provided by Poast plus ammonium sulfate, Poast alone, Fusilade 2000, Assure, and DPX-Y6202-31 applied at rates of 0.3 + 2.5, 0.4, 0.2, 0.125, and 0.125 lb ai/A, respectively. RE-45601 and DPX-Y6202-31 applied sequentially at 0.125 and 0.031 lb ai/A provided 610 and 634 lbs/A of seed cotton.



Reprinted from 1987 Proceedings: Beltwide Cotton Production Research Conferences pp. 344 - 345
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998