NC State Extension Publications

Description

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Smooth crabgrass (Digitaria ischaemum) germinates from March through early May in North Carolina when soil temperatures reach 53 to 58°F at a 4-inch depth. Alternating dry and wet conditions at the soil surface in the spring encourages germination. Crabgrass germinates and grows best when adequate light and moisture are present. Stems have a prostrate growth habit and may root at the lower nodes. Smooth crabgrass is similar to large crabgrass, but the leaf blade of large crabgrass has more hairs, with short hairs on both surfaces, and scattered hairs on the edges.

Cultural Control

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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.

Species Data

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  • SEEDHEAD / FLOWER
    • raceme; 2 - 6 spikes at top of stems
  • VERNATION TYPE
  • LIGULE TYPE
  • GROWTH SEASON / LIFE CYCLE
    • summer annual weed
  • AURICLE TYPE
    • absent
  • LEAF BLADE TIP SHAPE
    • sharp-pointed; smooth above, with mostly a few hairs near base, edges not hairy or sparse hairs along edge, dull green or tinged with purple
      Figure 5, Figure 6, Figure 7, Figure 8
  • LEAF BLADE WIDTH
    • 0.2 - 0.4 inches (5 - 10 mm) wide
      Figure 9
  • STOLON PRESENCE
    • present
  • RHIZOME PRESENCE
    • absent
  • COLLAR TYPE
  • SHEATH MARGIN
  • SHEATH TYPE
    • flattened; sheath is not hairy, lower sheaths may be sparsely hairy
      Figure 15
Smooth crabgrass vernation

Figure 1. Smooth crabgrass vernation.

Smooth crabgrass ligule

Figure 2. Smooth crabgrass ligule.

Smooth crabgrass ligule

Figure 3. Smooth crabgrass ligule.

Smooth crabgrass ligule

Figure 4. Smooth crabgrass ligule.

Smooth crabgrass leaf blade

Figure 5. Smooth crabgrass leaf blade.

Smooth crabgrass leaf blade

Figure 6. Smooth crabgrass leaf blade.

Smooth Crabgrass leaf blade

Figure 7. Smooth crabgrass leaf blade.

Smooth crabgrass leaf balde

Figure 8. Smooth crabgrass leaf blade.

Smooth crabgrass lead blade width

Figure 9. Smooth crabgrass leaf blade width.

Smooth crabgrass collar

Figure 10. Smooth crabgrass collar.

Smooth crabgrass collar

Figure 11. Smooth crabgrass collar.

Smooth crabgrass collar

Figure 12. Smooth crabgrass collar.

Smooth crabgrass sheath margin

Figure 13. Smooth crabgrass sheath margin.

Smooth crabgrass sheath margin

Figure 14. Smooth crabgrass sheath margin.

Smooth crabgrass sheath type

Figure 15. Smooth crabgrass sheath type.

Author

Extension Specialist (Turfgrass/Forage Crop Weed Mgt)
Crop & Soil Sciences

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Publication date: Nov. 9, 2017

Recommendations for the use of agricultural chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by NC State University or N.C. A&T State University nor discrimination against similar products or services not mentioned. Individuals who use agricultural chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage regulations and examine a current product label before applying any chemical. For assistance, contact your local N.C. Cooperative Extension county center.

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