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How to Manage Pests

Identification: Weed Photo Gallery

Large crabgrass

Scientific name: Digitaria sanguinalis Grass Family: Poaceae)

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Life stages of Large crabgrass collar flowering crabgrass seedling mature plant flowers and flower parts

Large crabgrass is a widely distributed summer annual grass that germinates throughout the summer. However, new seedlings may begin to appear as early as February. In California large crabgrass is found in the North Coast, southern Cascade Range foothills, Sierra Nevada foothills, Central Valley, central-western region, South Coast, and probably North Coast Ranges up to 3900 feet (1200 m) in elevation. It inhabits agricultural land and other disturbed sites. Once established, it is difficult to remove because it roots from portions of lower stems. It can provide good forage for livestock.

Habitat

Crop fields, orchards, vineyards, gardens, landscaped areas, turf, nurseries, pastures, roadsides, ditches, and other disturbed places.

Seedling

Seedlings sprout quickly. They are pale green and covered with coarse hairs. They form clumps with extensive but shallow roots where the soil is moist. Young leaves are rolled in the bud and unroll as they grow out of the center. Large crabgrass seedlings resemble those of witchgrass but are covered with shorter hairs.

Mature plant

Plants grow in clumps to about 2-1/2 feet (80 cm) tall, mostly upright, but sometimes prostrate. Stems are flat in cross-section, often purplish, and usually branched at the base. Leaves are flat, rolled in the bud and have a prominent midvein. It can be distinguished from smooth crabgrass, D. ischaemum, by its longer, narrower leaf, and presence of long stiff hairs on the sheath and on the upper and lower leaf surfaces. Leaves are about 1-1/4 to 8 inches (3–20 cm) long. In California smooth crabgrass is most often found in turfgrass whereas large crabgrass is more often found in gardens and landscaped areas.

Collar region

There is a membranous ligule but no auricles.

Flower

Flowering takes place from June through October. Flowers cluster along 3 to 7 slender, fingerlike branches that are located toward the end of the flowering stem. Although similar in appearance to the flower head of bermudagrass, Cynodon dactylon, the spikelike flower branches of large crabgrass arise separately from the stem; those of bermudagrass radiate from the same point. Spikelets are lance to egg shaped, and mostly less than 1/10 of an inch (about 3 mm) long.

Reproduction

Reproduce by seed.

Related species/Similar looking plants

Bermudagrass
Dallisgrass
Goosegrass
Smooth crabgrass
Witchgrass

More information


Statewide IPM Program, Agriculture and Natural Resources, University of California
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