Effect of Selected Post-Emergence Herbicides to Control Windmillgrass.

Windmillgrass (Chloris verticillata Nutt.) is a warm-season, bunch type perennial grass that is native to the United States. Plants are prolific seed producers, and as the name indicates, seeds are readily distributed by wind moving the rachis.  Recently, there are increasing reports regarding windmillgrass establishment in various turf areas, including residential lawns and utility turfs, in Missouri and surrounding states. Little is known regarding post-emergence (POST) herbicide options for selective control of windmillgrass in both warm- and cool-season turf.  A greenhouse experiment was conducted at the University of Missouri for evaluations of single application of seven selected herbicides, including fenoxaprop-p-ethyl, foramsulfuron, mesotrione, quinclorac, sulfentrazone, topramezone in tank-mixture with triclopyr, and a pre-packed product containing thiencarbazone-methyl, foramsulfuron, and halosulfuron-methyl, in addition to an untreated control. Treatments were arranged in a randomized complete block design with 4 replications, and this experiment was performed twice. At 4 weeks after treatment (WAT), windmillgrass receiving fenoxaprop-p-ethyl or topramezone tank-mixed with triclopyr reached 100% control. Mesotrione treated plants showed up to 50% shoot injury at 3 WAT. However, plants started to recover by 4 WAT. Other treatments showed limited effect on windmillgrass control. Further studies are ongoing to evaluate the effect of mesotrione in a tank-mixture with triclopyr, as well as a comparison of topramezone and triclopyr tank-mixtures.