Turf - Black Medic

Black medic is now flowering in turf areas. The following is information on this weed.

Black Medic (Medicago lupulina) is a yellowed flowered leguminous weed of turf and minimally maintained areas. It is related to alfalfa and has compound leaves that are arranged alternately with three, wedge to oval shaped leaflets. The center leaflet is stalked and the side leaflets occur close to the stem. The yellow flower is ball shaped but is smaller than white clover. Black Medic commonly occurs as a summer annual but can survive the winter as a tender perennial. It is common in compacted soils such as high traffic areas near sidewalks and is more prevalent in sites that receive limited nitrogen fertilization.

Many broadleaf post emergence herbicides have activity against Black Medic in turf; however 2,4-D will not provide control. Use of a product with triclopyr, dicamba, fluroxypyr, or clopyralid as an active ingredient is recommended. Drive (quinclorac), is effective against Black Medic and is also a good crabgrass herbicide. Spring applications made before the end of May are most effective. Black medic can be difficult to kill when under water stress and multiple applications may be needed in summer.

Gordon Johnson, Extension Horticulture Agent, UD, Kent County

Ornamentals Hotline Weed Pictures for Issue 19, August 3, 2007

White clover, an indicator of low mowing height and low fertility soil.

Spurge, an indicator of compacted soil.

Prostrate knotweed, an indicator of compaction.

Red Sorrel, an indicator of low pH, low fertility soil or dry soil.

Plantain, an indicator of low fertility soil.

Nutsedge and Oxalis (woodsorrel), indicators of wet soil.

Nimblewill, an indicator of excess shade.

Goosegrass, an indicator of compacted soil.

Crabgrass, an indicator of low mower height, wet soils, or high fertility.

Carpetweed, an indicator of dry soil.

Black Medic, an indicator of dry soil.

Bermudagrass (wiregrass), an indicator of low mowing height, compaction, or high fertility.

All Weed Pictures by Gordon Johnson, Extension Agent, Agriculture and Commercial Horticulture, University of Delaware, Kent County