How to Get Rid of Dallisgrass

Dallisgrass is a perennial weed commonly found throughout the southern states. Introduced to the United States from South America sometime before 1875, dallisgrass forms large, grassy clumps about the size of dinner plates and was initially used as a pasture grass. After you mow dallisgrass, the weed produces seed stalks with small, black seeds that spread by water, mowing, pets and humans. Unless you take proper steps to get rid of the dallisgrass either after seed germination or before, the weed continues to spread rapidly, infesting your lawn.

Things You'll Need

• Pre-emergent herbicide
• Post-emergent herbicide
• Glyphosate herbicide
• Garden shovel

Instructions

1. Spread pre-emergent herbicide over your lawn in the early spring and late summer. This stops the seeds from germinating and growing into mature weeds. Make sure you read the herbicide label carefully, confirming it is formulated for both your species of lawn grass and dallisgrass.

2. Apply a post-emergent herbicide once the temperature reaches above 75 degrees Fahrenheit. Allow the lawn to grow for two weeks before applying the herbicide. The more leaf area the weed has, the more surface the herbicide covers.

3. Wait to water your lawn at least 24 hours after applying the herbicide. Depending on the amount of the infestation, two more applications could be necessary, waiting 14 to 21 days between applications. Carefully read the product label of the post-emergent herbicide to confirm the use of the product on your lawn grass and for dallisgrass.

4. Treat the individual clumps of dallisgrass in St. Augustine grass and other lawn grasses where the spreading of pre-emergent and post-emergent herbicides could damage and kill the existing lawn. Spot-treat dallisgrass with herbicides whose active ingredient is glyphosate. Glyphosate is a non-selective herbicide, meaning it kills any vegetation it contacts. Read the label carefully, and don't use it on a windy day.

5. Dig up the dallisgrass from the soil. This is more effective with younger plants that have not had an opportunity to establish rhizomes. The rhizomes grow just beneath the surface of the soil and outward from the base of the mature weed. Since additional dallisgrass weeds sprout from the rhizomes, digging up a more mature weed may not rid your lawn of dallisgrass immediately.

References

• Agriculture and Natural Resources, University of California; Dallisgrass; M. LeStrange, et al.; July 2008
• PBI/Gordon Corporation: MSMA Herbicide
• University of Florida IFAS Extension; Preemergence Herbicides for Use in Ornamentals; Robert H. Stamps, et al.
• U.S. Forest Service; Glyphosate Herbicide Information Profile; February 1997
• Texas AgriLife Extension Service; Dallisgrass; Richard L. Duble
• "Neil Sperry's Complete Guide to Texas Gardening Second Edition"; Neil Sperry; 1991