Dallisgrass is a perennial grassy weed that is also known by its scientific name, Paspalum dilatatum. This lawn weed can reach heights of up to 5 feet.
Dallisgrass can be identified as a coarse-textured, robust, clumping, perennial grassy weed. It features a tall, rounded ligule and a smooth, broad collar. The sheaths are compressed with a prominent mid-vein that is sometimes hairy. Dallisgrass features flat blades with sparse hairs near the ligule, plus its blade edges are rough—even though both surfaces are smooth. This lawn weed also has a seed head that is produced on a terminal stalk reaching up to 5 feet in height. The seed head includes three to five spikes branching from the center, with each spike measuring 2 to 4 inches long and containing four rows of spikelets. Dallisgrass reproduces by very short rhizomes and seeds in the summer.
This grassy weed prefers marshes and damp to wet habitats that are developed or disturbed by civilization. It frequently grows in pastures, lawns, golf courses and other turf areas. In the United States, Dallisgrass commonly grows in states that fall in the humid subtropical climate zone. These perennial grassy weeds can germinate and spread from seeds, but they also produce a root structure (tubers, bulbs or corms) that can birth new weeds from your lawn’s surface (using stolons) or from underground (using rhizomes). Perennial grassy weeds live two or more years and have a deeper root structure that can give rise to new weeds—even if you no longer see the weeds in your lawn.
It is possible to remove Dallisgrass through cultural control methods—such as hand-pulling lawn weeds or proper watering and mowing—however, these methods are time-consuming. Still, these cultural weed control practices are highly recommended for getting rid of Dallisgrass in your lawn and landscaping. This is due to the limited number of options to kill this grassy weed.