What Does Crabgrass Look Like?
Identification
Crabgrass, scientifically known as Digitaria, is a common annual weed that can be a nuisance in lawns and other areas. It gets its name from its sprawling stems that resemble the legs of a crab. Crabgrass has broad, flat blades and produces long flower clusters and thousands of seeds per growing season.
Types of Crabgrass
There are two main types of crabgrass: smooth crabgrass and hairy crabgrass. Smooth crabgrass is more common.
- Smooth Crabgrass: Has no hairs around the sheath or leaves. The leaves taper to a point, and the stems bend at the nodes.
- Hairy Crabgrass: Has tiny hairs on the leaves and stems. The leaves are broader than smooth crabgrass and can be up to 1/2-inch wide.
Life Cycle
Crabgrass is an annual plant, meaning it lives for one year. It begins its life cycle in the spring when the soil temperature reaches 55 degrees Fahrenheit. The seeds germinate and the seedlings resemble miniature corn stalks. As the seedlings grow, the leaves start to branch out.
Crabgrass thrives in hot and dry weather conditions. It is drought tolerant and can often be the last green thing on the lawn before a late fall frost kills it.
Spread
Crabgrass spreads by seed. If the seeds are not prevented from germinating, they will develop roots and emerge as new plants. Sprouted crabgrass can grow more vigorously if its long stems are allowed to flop over and touch the ground. The stems can root at the nodes, and secondary stems can sprout off the main stem, a foot or two away from the main crown.
Prevention
The best way to prevent crabgrass is to stop the seeds from germinating. This can be done by using a pre-emergent herbicide in the spring. Pre-emergent herbicides create a barrier on the soil surface that prevents the seeds from absorbing water and germinating.
Control
If crabgrass has already germinated, it can be controlled with a post-emergent herbicide. Post-emergent herbicides target specific weeds or plant categories, such as grassy versus broadleaf plants. It is important to read the herbicide label carefully and follow the instructions for application.
Other methods of crabgrass control include:
- Maintaining a healthy lawn by mowing high and fertilizing
- Hand-pulling large seedlings
- Removing dead crabgrass plants
- Reseeding bare lawn spots with healthy lawn grass
- Mulching non-lawn areas
Additional Tips
- Crabgrass seeds can be spread by wind and animals. Even if you successfully control crabgrass on your property, it is possible for seeds from neighboring properties to blow over and germinate in your lawn.
- It is important to reapply pre-emergent herbicide every year to prevent crabgrass from germinating.
- Post-emergent herbicides can kill crabgrass permanently, but they do not prevent new seeds from germinating.