Back To Search Results
||Crabgrass, large (hairy)
- Pest Type: Weed
- Crops Affected: Wheat, Cotton, Potatoes, Soybeans, Corn
- Scientific Name: Digitaria sanguinalis
- Pest Order: Poaceae
Large crabgrass is a summer annual grass that can grow prostrate and spreading or ascending to 1 m in height.
Reproduction is by seeds which germinate from mid-spring through late summer. Vegetative spread can also occur by rooting systems, this is not a primary means of propagation.
The first leaf blade is lanceolate to linear, about 3-4 times longer than wide, and opens parallel to the ground. Crabgrass seedlings are upright. Leaves are linear with tapered leaf tips, about 10 times longer than wide (5-12 cm long and 4-12 mm wide). Leaves are rolled in the bud, lack auricles, and have a jagged membranous ligule. There are stiff hairs on the blade and sheath.
Leaves are similar to those of seedlings. Stiff hairs on the blade and sheath are at a 90-degree angle to the plant surface. The collar is broad with long hairs at the margin. Blades are about 12 times longer than wide.
Leaves are similar to those of earlier stages. Leaf blades are about 12 times longer than wide (3-20 cm long and 3-14 mm wide) and have hairs on both surfaces and on the sheath. Mature plants have compressed sheaths. Tillering begins about the 4-5 true-leaf stage (late spring and early summer). Tiller internodes elongate later in the summer. Elongated stems may root at the nodes. On maturing plants, older sheaths and leaves may turn dark red or maroon.
Roots are fibrous, with adventitious roots arising from the nodes of elongated tillers.
Flowering occurs in mid to late summer. The seedhead commonly consists of 3-5 spikes clustered at the top of stems. Spikelets are elliptic and in 2 rows along the spike. Each spikelet contains a single shiny, yellow-brown seed (2-3 mm long).
Large crabgrass plants die with the first killing frost, and remain as brown clumps. They are long wire-like stems and seedheads that will persist well into the winter.
Large crabgrass is a common weed of most agronomic and horticultural crops, as well as turf and landscape areas. It can tolerate poor soil and dry conditions, but is found in nearly every soil type and crop. It is also common along roads and in waste areas.
Common throughout the United States as well as other temperate and tropical regions of the world.
Smooth crabgrass is similar but has few hairs on the leaf blade and sheath, and is generally smaller. Southern crabgrass has hairs on the sheaths but lacks hairs on the blades and is more common in the southeastern United States.