SafePlants

Crabgrass: The Unwanted Guest

Crabgrass, a common nuisance in lawns and gardens, is known for its tenacious growth and ability to quickly spread. Understanding its characteristics and control methods is key to maintaining a healthy lawn.

Scientific Name and Common Names

• Scientific Name: Digitaria (genus)
• Common Names: Crabgrass, Finger-grass, Fonio

Taxonomy and Nomenclature

• Family: Poaceae (Grass family)
• The text mentions Digitaria sanguinalis (Large Crabgrass) as a specific species.

Distribution and Habitat

Crabgrass is native to tropical and warm temperate regions. It has been introduced to and naturalized in North America, where it is considered a common weed in lawns and cultivated areas. The text also mentions its prevalence in Colorado and Connecticut lawns.

Ecological Role

• Crabgrass is often considered an invasive species in lawns and gardens due to its rapid growth and ability to outcompete desirable grasses. It can form dense mats that smother other plants.

Morphological Characteristics and Growth Habits

• Crabgrass is an annual grassy weed that spreads along the ground.
• Large crabgrass (Digitaria sanguinalis) is described as purplish or green with hairy leaves and sheaths. Its leaves are about 1/4 to 1/3 inch wide. The seedheads have 2-9 "branches" and appear purplish when mature.
• Smooth crabgrass starts as a light green color and turns to a darker, dull green as it matures, forming flattened stems.

Interactions with Other Organisms

• Crabgrass outcompetes other plants for resources.

Control Methods

• The text extensively covers various methods for controlling crabgrass, including:
  • Preemergence and postemergence herbicides (chemical methods)
  • Cultural control practices (e.g., proper lawn care)
  • Organic approaches

Resources and Further Information

• University of Connecticut
• UC home and landscape guidelines