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ARS Home » Southeast Area » Tifton, Georgia » Crop Protection and Management Research » Research » Publications at this Location » Publication #149237
Title: BERMUDAGRASS (CYNODON SPP.) DOSE-RESPONSE RELATIONSHIPS WITH CLETHODIM, GLUFOSINATE, AND GLYPHOSATE

Author
item Webster, Theodore
item Hanna, Wayne
item MULLINIX, JR., BENJAMIN - UNIVERSITY OF GEORGIA

Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/26/2004
Publication Date: 8/6/2004
Citation: Webster, T. M., Hanna, W. W., Mullinix, Jr., B. 2004. Bermudagrass (Cynodon spp.) dose-response relationships with clethodim, glufosinate and glyphosate. Pest Management Science. 60:1237-1244.

Interpretive Summary: Methyl bromide is the most common soil fumigant used in the turfgrass industry, important in renovation programs when a new turfgrass replaces an older cultivar. Contamination of new turfgrass by the previous one can create significant problems due to potential differences among cultivars (e.g. pest tolerance and mowing requirements). However, use of methyl bromide must stop in 2005. One alternative to methyl bromide in turfgrass renovation involves the development of non-pollen and non-seed forming herbicide-resistant turfgrasses. Herbicide-resistant bermudagrass cultivars could allow managers to more efficiently manage weeds with environmentally benign herbicides. Commercially available cultivars and those under development in the Tifton bermudagrass breeding program (non-genetically modified organisms) were evaluated for their sensitivity to three common herbicides. Relative to other cultivars, common bermudagrass was intermediate in its response to clethodim and among the most tolerant cultivars to glufosinate and glyphosate. TifSport exhibited relative tolerance to clethodim and glufosinate compared with other cultivars, but relative sensitivity to glyphosate. One cultivar, 94-437, was consistently among the most sensitive cultivars to each of the herbicides. While there were differential herbicide tolerances among the tested bermudagrass cultivars, there did not appear to be any naturally occurring herbicide-resistance that could be commercially utilized.

Technical Abstract: Greenhouse studies were conducted to evaluate the sensitivity of 12 bermudagrass cultivars to clethodim, glufosinate, and glyphosate. Each herbicide was applied at eight doses. Data were regressed on herbicide dose using a log-logistic curve (R2 = 0.56 to 0.95 for clethodim, R2 = 0.60 to 0.94 for glufosinate, and R2 = 0.70 to 0.96 for glyphosate). The herbicide rate that elicited a 50% plant response (I50) in the bermudagrass cultivars ranged from 0.04 to 0.19 kg/ha clethodim, 0.19 to 1.33 kg/ha glufosinate, and 0.34 to 1.14 kg/ha glyphosate. Relative to other cultivars, common bermudagrass was intermediate in its response to clethodim and among the most tolerant cultivars to glufosinate and glyphosate. TifSport exhibited relative tolerance to clethodim and glufosinate compared with other cultivars, but relative sensitivity to glyphosate. One cultivar, 94-437, was consistently among the most sensitive cultivars to each of the herbicides. While there were differential herbicide tolerances among the tested bermudagrass cultivars, there did not appear to be any naturally occurring herbicide-resistance that could be commercially utilized.