Water grass Paspalum dilatatum

Paspalum dilatatum, or Dallis grass, is a common perennial weed often found in lawns and disturbed areas. It is an invasive bunchgrass and its dense growth habit tends to smother and prevent other native species from flourishing. Its rapid growth and profuse seed production enable it to quickly invade agricultural land, especially rice fields, waterway margins, and managed urban sites. However, it is sometimes used as a summer forage grass in pastures. If it is to be used in pastures, try to maintain a height of 2 to 3" because a lower grass height can result in a decline of the grass.

Dallis grass spreads from a short rhizome and has thick and deep fibrous roots. The leaf stalks are hollow and form a coarse, spreading tuft, while the leaves themselves are blade-shaped and grow up to 10 inches long. The lower sheaths of the leaves are somewhat hairy, but the leaf blades are hairless. There are typically 3 to 7 groups of flowers (racemes) on a stem, each less than 2 inches long, forming at nearly right angles to the stem. The flower is small, fleshy, inversely coned shaped and 3-lobed. It forms at the opening of the flower bud.  

A major component of Dallis grass management is preventing the establishment of new plants. In home landscapes, digging out young plants before they form rhizomes or set seed is the best strategy for control. Mature plants can also be dug out, but they sometimes grow back if rhizomes are left behind.

Insects, Diseases and Other Plant Problems:  Seed heads are susceptible to an ergot fungus, Calviceps paspali, that is toxic to livestock when ingested. This is a weedy plant and is listed as invasive in SC and KY.  This species is classified as invasive by the NC Invasive Plant Council.