Weeds flourishing in lawns

Warm temperatures and lack of rainfall are causing thinned turf, bringing the arrival of weeds including black medic, white clover and crabgrass.

Once again this summer, black medic (Medicago lupulina) appears to be one of the weeds that are everywhere. The cool, wet spring that resulted in vigorous turfgrass growth also resulted in many fertilizer applications not lasting as long as normal. The recent, warm temperatures and lack of rainfall have resulted in thinned turf where weeds including black medic, white clover and, of course, crabgrass are invading.

Black medic and white clover are similar in that you often find them growing on low fertility, low maintenance sites. The most effective herbicides for controlling black medic and white clover contain the active ingredient clopyralid, fluroxypyr or quinclorac. In un-irrigated turf, you may want to wait for moisture to return before trying to control the weeds. If you have irrigated turf and it’s a serious infestation, you may want to try and control it now to prevent a complete takeover and then make another application in the fall to clean up any misses or weeds that didn’t quite get eliminated.

Quinclorac is also very effective at controlling crabgrass. It is available as a stand-alone herbicide or you can find it in combination products. Always remember to read and follow label directions when applying herbicides.

Please see MSU Turf Weeds.net for all your turfgrass weed identification and management recommendations.

Dr. Frank’s work is funded in part by MSU‘s AgBioResearch.

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