Herbicides are Effective for Reducing Dense Native Warm-season Grass and Controlling a Common Invasive Species, Sericea Lespedeza

Practices within the Conservation Reserve Program promote planting native grasses and forbs to improve habitat for northern bobwhite (Colinus virginianus) and other wildlife. However, native grasses often become dense and stands can be invaded by undesirable plant species that reduce habitat quality. We investigated three herbicides (clethodim, glyphosate, and imazapyr) at two rates to reduce native-grass density and five herbicides (aminopyralid, fluroxypyr+triclopyr, glyphosate, metsulfuron-methyl, and triclopyr) at two rates to control sericea lespedeza (Lespedeza cuneata), a common nonnative invasive species. We applied herbicide to reduce native grass cover at four sites in Kentucky and Tennessee in 2013–2014. We applied herbicide to control sericea at three sites in Kentucky in 2012–2013. We recorded vegetation composition at the end of the first growing season (1GAT) after treatment and the beginning of the second growing season (2GAT) after treatment. Both rates of glyphosate and imazapyr and the full rate of clethodim reduced native grasses 1GAT. Both rates of glyphosate and the full rate of imazapyr reduced native grasses 2GAT, but forb cover was increased 2GAT only with full-rates. Triclopyr, fluroxypyr+triclopyr, and glyphosate treatments reduced sericea 1GAT and 2GAT. We recommend applications of imazapyr (53.1% active ingredient (AI), 24 oz/acre) or glyphosate (42% AI, 2 qt/acre) to reduce dense native grass cover and increase forb cover. However, if desirable forbs are present, especially legumes, imazapyr should be used. We recommend glyphosate (42% AI, 1 qt/acre), fluroxypyr+triclopyr (16% and 45% AI, 12 oz/acre), or triclopyr (44%, 16 oz/acre) to control sericea lespedeza.