Weeds in the heat

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.    

In the last several issues of the Landscape CAT Alert, I’ve discussed different weeds that may be thumbing their nose at you this summer. Now that the heat has increased to the point where air conditioners are a valued commodity those weeds may become even more persistent. Crabgrass is certainly enjoying this latest stretch of high temperatures, and I’ve also seen some nice patches of yellow nutsedge taking hold in turfgrass. Yellow nutsedge control options for professional applicators include Certainty (a.i. sulfosulfuron) and Sedgehammer (a.i. halosulfuron). Repeat applications will likely be required to achieve control.

As with any herbicide applications at this time of year, be very careful of applications to turfgrass that is under drought/heat stress. General recommendations are to avoid herbicide applications when temperatures are above 80°F due to the risk of burning the turf.

In addition to the crabgrass, nutsedge, and black medic, clover is catching a lot of attention right now with its white flowers seeming to dominate the landscape. When clover is not flowering, it’s amazing how often it is simply ignored, but once it flowers it gets everyone’s attention. Clover often becomes a problem in turfgrass areas that are not receiving adequate fertilization, so the easiest recommendation for reducing clover infestations over time is to fertilize the turf. Broadleaf herbicide applications at this time of year can be effective for controlling clover, assuming you can avoid the high temperatures. However, fall is still the best time to control broadleaf weeds including clover.

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