Identification: Birdsfoot trefoil is a low-growing perennial broadleaf weed . It has a prostrate growth pattern, meaning that it spreads throughout the turf canopy via mat-like stolons and rhizomes. Also referred to as cat’s-clover or devil’s-claw, birdsfoot trefoil is primarily identifiable by its unique-shaped leaves that alternate on the main stem, are trifoliate (3 terminal leaflets at the apex), and have two smaller (wing-like) leaves at the base of the leaves. Leaves can be oval- or oblong-shaped with a point at the apex and identifiable by its distinct blue-greenish color. The main stem is flat (partially square) shaped on the top, rounded on the base and can be sparsely hairy or smooth. Large, bright yellow flowers are produced in late June through the fall in open (clover-like) clusters. Eventually, fruit resembling pea pods develop that are arranged in the shape of a bird’s foot, thus explaining its common name. It may be mistaken for black medic or some clovers; however, birdsfoot trefoil has completely/or nearly entire (smooth) leaf margins. Though black medic also has yellow flowers, they are often smaller and more numerous (clusters) than birdsfoot trefoil flowers.
Cultural control: Proper turf such as adequate mowing heights, irrigation, and fertilization will help to produce a dense, aggressive turf which is the greatest defense against invading weeds. Birdsfoot trefoil often thrives in soils that are drought-prone or have low fertility; thus, fertilizing with nitrogen containing fertilizers will help reduce birdsfoot trefoil. Physical removal, such as hand-pulling or cultivation (e.g. hoeing) may also provide adequate weed management when populations are small. Although it is important to remove as much below-ground tissue as possible to prevent regrowth.
Biological control: None known for control of birdsfoot trefoil.
Chemical control: There are nonselective and selective control options available for birdsfoot trefoil postemergence (POST) control. Selective POST weed control on birdsfoot trefoil can be achieved with applications of herbicides containing 2,4-D + dicamba + MCPP as well as other herbicide mixtures. Herbicides that contain triclopyr (Turflon Ester) or triclopyr in combination with other herbicides can also control birdsfoot trefoil in cool season grasses.
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Aaron Patton, Turfgrass Extension Specialist
Leslie Beck, Postdoctoral Research Associate