Efficacy of Spring Herbicide Applications for Fescue Control: A Comparison of Three Products

The Conservation Reserve Program (CRP) was designed to remove highly erodible cropland from production. Although wildlife habitat benefits are an important component of CRP, millions of hectares of CRP do not produce optimal wildlife benefit because of poor cover crop choice. Kentucky-31 tall fescue (Festuca arundinacea; hereafter, fescue) was one of the most commonly planted grasses on CRP fields but provides relatively poor habitat for grassland birds such as northern bobwhites (Colinus virginianus). Control of fescue and release of a latent native plant community may enhance habitat value of CRP fields for northern bobwhite and other grassland birds. During 1999-2000, we evaluated effects of various spring herbicide applications, both singular and in combination, on vegetation structure and composition in fescue-dominated CRP fields. Glyphosate produced the poorest fescue control, released an undesirable johnsongrass (Sorghum halepense) stand, and suppressed legumes. Imazapyr controlled fescue in both the first and second growing seasons post-treatment and did not reduce abundance of legumes, but provided little residual johnsongrass control. Imazapic controlled fescue, did not reduce legumes, and provided residual control of johnsongrass. Imazapic in combination with glyphosate also reduced fescue and controlled johnsongrass but suppressed legume establishment. Our results suggest that all the herbicide treatments we tested can reduce fescue; however, they have different effects on johnsongrass and legumes. We recommend managers use imazapic when attempting to control tall fescue and johnsongrass and promote legume restoration. Imazapyr also is an effective herbicide if johnsongrass control is not a conservation concern.

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