Large Crabgrass

Grass (Poaceae family):

Digitaria sanguinalis (L.) Scop.

EPPO code:

DIGSA

Other names:

Finger grass, hairy crabgrass, tumbleweed

Species information

Lifecycle:

Annual.

Propagation:

Reproduces by seed.

Emergence:

Usually, large crabgrass is one of the last annual grass species to emerge. It is considered a mid- to late-season weed.

Habitat:

Large crabgrass is commonly found in cultivated fields and lawns throughout Ontario.

Competitiveness:

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

Resistance:

There are large crabgrass populations resistant to Group 1 (for example, quizalofop, sethoxydim) herbicides in Ontario.

Identification clues

Auricles:

None.

Ligule:

Membranous.

Leaf blade:

Hairy on both sides.

Leaf sheath:

Hairy, although the margin of the leaf sheath is hairless.

Stem:

Round.

Seed heads:

Finger-like with several thin and slender spikes.

Roots:

Fibrous.

Often mistaken for

I know it's not Proso millet because large crabgrass has a membranous ligule, but proso millet has a hairy ligule.

I know it's not Smooth crabgrass because large crabgrass is extremely hairy, but smooth crabgrass is relatively hairless.

I know it's not Witchgrass because large crabgrass has a membranous ligule, but witchgrass has a hairy ligule.