Large crabgrass (Digitaria sanguinalis), also called hairy crabgrass, is a common weed in turfgrass situations, and can germinate from March through early May in North Carolina when soil temperatures reach 53 to 58°F at a 4-inch depth. This weed is found in a variety of habitats. Germination of this weed is encouraged by the alternating dry and wet conditions at the soil surface in the spring. Stems have a prostrate growth habit and may root at the lower nodes. Large crabgrass is similar to smooth crabgrass. However, the leaf blade of smooth crabgrass is not as hairy, with a few hairs near the base of the blade. Leaf blade edges of smooth crabgrass are either not hairy or have sparse hairs.

Crabgrass will grow under close mowing conditions. Competition is enhanced by thin open turfgrass stands, improper mowing heights for the desired turf, summer fertilization, and light, frequent irrigation. For crabgrass control, practice procedures outlined to maintain a dense, actively growing turf.

• SEEDHEAD / FLOWER
  • raceme; 2 - 9 spikelets arising from different points along the top of stems
    Figure 1, Figure 2, Figure 3
• VERNATION TYPE
  • leaves rolled in the bud
    Figure 4
• LIGULE TYPE
  • membranous; 0.04 - 0.08 inches (1 - 2 mm) long, rounded to sharp pointed, toothed, often reddish
    Figure 5
• GROWTH SEASON / LIFE CYCLE
  • summer annual weed
• AURICLE TYPE
  • absent
    Figure 6
• LEAF BLADE TIP SHAPE
  • sharp-pointed; covered with short hairs on both surfaces, sharply creased below, edges rough with scattered hairs
    Figure 8
• LEAF BLADE WIDTH
  • 0.2 - 0.6 inches (5 - 15 mm) wide
    Figure 7
• STOLON PRESENCE
  • present
    Figure 9, Figure 10
• RHIZOME PRESENCE
  • absent
• COLLAR TYPE
  • indistinct, mostly divided, hairy edges
    ​Figure 11, Figure 12
• SHEATH MARGIN
  • open
• SHEATH TYPE
  • flattened; sheath has long hairs; often with purple veins
    Figure 13

Figure 1. Large Crabgrass seedhead.

×

Figure 1. Large Crabgrass seedhead.

Print Image

Figure 2. Large Crabgrass seedhead.

×

Figure 2. Large Crabgrass seedhead.

Print Image

Figure 3. Large Crabgrass seedhead.

×

Figure 3. Large Crabgrass seedhead.

Print Image

Figure 4. Large Crabgrass vernation.

×

Figure 4. Large Crabgrass vernation.

Print Image

Figure 5. Large Crabgrass ligule.

×

Figure 5. Large Crabgrass ligule.

Print Image

Figure 6. Large Crabgrass auricle.

×

Figure 6. Large Crabgrass auricle.

Print Image

Figure 7. Large Crabgrass leaf blade width.

×

Figure 7. Large Crabgrass leaf blade width.

Print Image

Figure 8. Large Crabgrass leaf blade tip.

×

Figure 8. Large Crabgrass leaf blade tip.

Print Image

Figure 9. Large Crabgrass stolon presence.

×

Figure 9. Large Crabgrass stolon presence.

Print Image

Figure 10. Large Crabgrass stolon presence.

×

Figure 10. Large Crabgrass stolon presence.

Print Image

Figure 11. Large Crabgrass collar type.

×

Figure 11. Large Crabgrass collar type.

Print Image

Figure 12. Large Crabgrass collar type.

×

Figure 12. Large Crabgrass collar type.

Print Image

Figure 13. Large Crabgrass sheath.

×

Figure 13. Large Crabgrass sheath.

Print Image