Golf Course Management

OCT 2013

Golf Course Management magazine is dedicated to advancing the golf course superintendent profession and helping GCSAA members achieve career success.

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research Glyphosate-tolerant perennial ryegrass and Poa annua control Using glyphosate-tolerant perennial ryegrass to overseed bermudagrass can give superintendents an edge on Poa annua. Two glyphosate-tolerant perennial ryegrass (Lolium perenne) cultivars, JS501 and Replay, have recently been released for commercial use. Once these perennial ryegrasses are mature, glyphosate can be applied to these cultivars for weed control without injury to the turf. Tese cultivars were produced through conventional plant breeding and are not genetically modifed organisms (GMOs). Managing glyphosate-resistant cultivars Research conducted in permanent perennial ryegrass areas has concluded that glyphosate at 0.26 pound acid equivalent (ae)/acre (0.29 kilogram ae/ Michael L. Flessner J. Scott McElroy, Ph.D. 90 GCM October 2013 hectare) is safe to JS501 and Replay and results in over 90% annual bluegrass (Poa annua) control. Glyphosate at 0.52 pound ae/acre resulted in less than 10% injury (2). Other published work (3,4) has also indicated that glyphosate at 0.26 pound ae/ acre is adequate to control annual bluegrass. Previous research has also indicated that both JS501 and Replay must be mature before glyphosate application or injury and stand reduction will result. Glyphosate application at rates greater than 0.26 pound ae/acre should not be used three to four weeks after seeding to avoid unacceptable injury and cover reduction (1). In the same study, the researchers found that glyphosate applications The research site was at the Auburn University Turfgrass Research and Education Center in Auburn, Ala. This photo was taken on Feb. 22, 2011, during the frst year of the study. Photos by M. Flessner

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