White clover and black medic infesting turf

White clover and black medic are both currently flowering in lawns and other turf.

Once again, the broadleaf weeds black medic (Medicago lupulina) and white clover (Trifolium repens) are infesting turf. These weeds are commonly found growing on low fertility, low maintenance sites such as roadsides, boulevards and neglected home lawns.

Black Medic
Black medic in a lawn

The characteristic that makes these species competitive in low fertility sites is the fact that they host rhizobacteria that fix atmospheric nitrogen into plant-available nitrogen. Of course with the extended start to the growing season, the typical fertilizer programs may result in some leaner than normal turf as application intervals may be stretched to the limit, thereby making these weeds even more competitive with hungry turf.

The most effective herbicides for controlling black medic and white clover contain the active ingredient clopyralid, fluroxypyr or quinclorac. In unirrigated turf, ensure there is adequate soil moisture before trying to control the weeds. In irrigated turf, and if it’s a serious weed infestation, you may want to control the weeds 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.

Always remember to read and follow label directions when applying herbicides. Please see www.msuturfweeds.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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