How Can I Control Dallisgrass?

Do you want to try controlling dallisgrass with cultural control methods?

Do you want to prevent a dallisgrass infestation?

Do you want to control established dallisgrass weed in turfgrass?

Do you want to control dallisgrass seeds in turfgrass?

Dallisgrass can be introduced into lawn areas with new turfgrass seed or sod, but often the seed is introduced on mowers that have been used in contaminated sites and then moved to weed-free sites. Cleaning a mower after mowing a contaminated site should reduce the chance of invasion into new areas. Inspect sod before taking delivery to make sure dallisgrass is not present. Don’t use soil from dallisgrass-contaminated areas to repair low or bare spots in lawns. In dallisgrass-infested areas delay or minimize the amount of aeration performed on the turfgrass in spring when new seedlings germinate to avoid small open areas where dallisgrass plants might become established.

Because dallisgrass is a perennial plant, persistence is required to kill it with cultural practices. In lawn areas, the clumps can be removed by digging. Mowing the turfgrass will not remove dallisgrass, but when turfgrass is mowed at its optimum height, it is better able to resist an invasion of this weed. Dallisgrass is not normally a problem in ornamental beds, but if it does occur, the plants can be dug out and a thick layer of mulch laid over the area to control the seedlings. Along roadsides and fences or in orchards and vineyards, the plants can be dug out during summer and left in place for the clumps of rhizomes to dry.

The post-emergent herbicides MSMA or CMA can be used by home gardeners to control clumps of dallisgrass growing in lawns. These herbicides are relatively selective and must be applied two to three times at 3-week intervals in the summer. The turfgrass and dallisgrass should be in good growing condition before application. Also, it is best if the turf is left unmowed for 2 weeks before the first application to create the maximum amount of leaf area for coverage by the herbicide spray. Withhold irrigation for 24 hours after application.

Preemergent herbicides can be used in established turfgrass to control germinating dallisgrass seed. Apply preemergent herbicides in late winter or early spring before the dallisgrass seed germinates. Herbicides that control crabgrass such as benefin + oryzalin, bensulide, DCPA, dithiopyr, oryzalin, oxadiazon pendimethalin, or prodiamine, are also effective on dallisgrass. Preemergent herbicides used on lawns need to be irrigated into the soil with about 1/2 inch of water relatively soon after application to become effective. Consult the label for application details.

In ornamental or noncrop areas, glyphosate can be used as a nonselective treatment to control established plants. Apply glyphosate when dallisgrass is flowering but before the seed has been produced. The preemergent herbicides napropamide, oryzalin, pendimethalin, or combinations of benefin plus oryzalin are effective to prevent dallisgrass seed from germinating.