Influence of Mowing Timing Before or After a Herbicide Application On Ground Ivy Control.

Ground ivy (Glechoma hederacea), sometimes referred to as creeping Charlie, is a tough-to-control broadleaf weed in the mint family usually found growing in the shade. When attempting to control weeds, Extension bulletins and many herbicide labels recommend not to mow turf 1-2 days before or after application of a herbicide to maximize control. However, the effect of mowing on herbicide efficacy has not been sufficiently explored. The objectives of this experiment were to 1) determine which herbicides most effectively control ground ivy, 2) determine the optimum mowing schedule for weed control, and 3) determine if any herbicide by mowing timing interactions exist. Herbicide treatments of 2,4-D ester, metsulfuron, aminocyclopyrachlor, 2,4-D + MCPP + dicamba, triclopyr, and the untreated check were applied with various mowing treatments in late October of 2010 and 2011 in separate experimental areas. Mowing treatments included 1) herbicide applied before mowing, 2) herbicide applied after mowing, and 3) no mowing within 72 hours of herbicide application. The main effect of herbicide was significant on each rating date beginning two weeks after application with aminocyclopyrachlor providing the most ground ivy control each year. All other herbicides reduced ground ivy coverage compared to the untreated check. In both years of the experiment, the main effect of mowing across all herbicide treatments did not have a significant impact on ground ivy coverage when rated the following June. No significant mowing by herbicide interaction was present on the majority of the rating dates. However, a significant mowing by herbicide interaction was present on two of nine rating dates with no consistent herbicide or mowing treatment responsible for the interaction. Thus, this data suggests that whether or not turf is mown before or after an herbicide application may not be as important as previously thought.