Dallisgrass (Paspalum dilatatum) is a perennial grass from South America considered a turfgrass weed in the United States. Dallisgrass grows underground rhizomes and produces large amounts of seed. Dallisgrass is challenging to manage and large patches of it may require the use of herbicide. Make sure that the lawn is healthy and growing prior to treatment, don’t spray herbicides on hot days, and refrain from mowing the lawn for the two weeks prior to treatment.
Remove new dallisgrass as it appears by digging it out of the ground with the hoe. If you dig out more mature plants, make sure that you remove the entire underground rhizome.
Apply pre-emergent herbicide in the spring. Check the label of the product to make sure it is safe to use on your particular type of turf and follow the application instructions.
Apply post-emergent herbicide, such as Weed-Hoe or Weed-B-Gon, as the dallisgrass emerges in the summer. Again, check the label to make sure the herbicide is safe to use on your lawn. Small patches of dallisgrass can be sprayed individually, but larger infestations will require the use of a tank sprayer. Apply the herbicide at three week intervals, two or three times during the summer.
Water the lawn two days after the herbicide application. Mow the lawn three days after treatment.