Smooth Crabgrass

Grass (Poaceae family):

Digitaria ischaemum (Schreb,) Muhl.

EPPO code:

DIGIS

Other names:

Finger grass, small crabgrass

Species information

Lifecycle:

Annual.

Propagation:

Reproduces by seed.

Emergence:

Typically, smooth crabgrass is one of the later-emerging annual grasses.

Habitat:

Smooth crabgrass is commonly found in cultivated fields throughout Ontario. It is also common in lawns.

Competitiveness:

Agriculture and Agri-Food Canada research has shown that smooth crabgrass densities of 20,000 plants/ac can result in a 3% yield loss in corn and soybeans.

Identification clues

Auricles:

None.

Ligule:

Membranous.

Leaf blade:

As its name suggests, the leaf blade of smooth crabgrass is smooth on both sides.

Leaf sheath:

Smooth crabgrass’ leaf sheath is also smooth and its margins are hairless. There are a few hair near the collar on the basal leaves (1^st to 4^th).

Stem:

Its stem is round, and typically it has a prostrate growth pattern.

Seed heads:

Seed heads are finger-like and covered in several thin spikes.

Roots:

Fibrous.

Often mistaken for

I know it's not Large crabgrass because large crabgrass is extremely hairy, while smooth crabgrass is mostly hairless.