Smooth Crabgrass

Weeds

crabgrass

Digitaria ischaemum

Photos

Smooth crabgrass is the most common summer annual grass problem in managed turf. It is estimated that 90% of the crabgrass in Michigan lawns is smooth crabgrass. Smooth crabgrass lacks the hairs of large crabgrass and can be identified by its light green appearance and swollen, zig-zag nodes. Crabgrass is a summer annual that re-establishes from seed every spring. Crabgrass can be an indication of elevated soil temperatures and will often establish in last year's grub damaged areas.

Crops Affected: turf

Management

Elevated mowing heights and judicious nitrogen fertilization can be extremely effective at reducing competition from crabgrass. Research studies have shown up to 95% reduction in crabgrass when mowing height is increased from 1.5 to 3.0 inches. Thin turf in the spring or drought conditions often lead to major infestations of crabgrass.

Similar Species

Large and smooth crabgrass can be distinguished by the presence (large) or absence (smooth) of hair on the upper and lower leaf surfaces and the stems.
Look alikes include Giant Foxtail, Green Foxtail, Large Crabgrass, and Tall Fescue.

MSU Extension Turf