Plant Profile: Paspalum dilatatum

Paspalum dilatatum, commonly known as Dallis grass, is a prevalent perennial weed typically found in lawns and disturbed environments. This invasive bunchgrass has a tendency to grow densely, which can overshadow and inhibit the growth of native plant species. Its rapid growth rate and prolific seed production allow it to swiftly take over agricultural areas, particularly rice fields, the edges of waterways, and urban landscapes. Despite its invasive nature, Dallis grass is occasionally utilized as a summer forage option in pastures. When incorporating it into pastures, it is advisable to maintain a height of 2 to 3 inches, as cutting it shorter may lead to a decline in its health.

Dallis grass propagates through short rhizomes and possesses thick, deep fibrous roots. The leaf stalks are hollow and create a coarse, spreading tuft, while the leaves are blade-like and can reach lengths of up to 10 inches. The lower sheaths of the leaves exhibit some hairiness, whereas the leaf blades are smooth. Typically, a stem will bear 3 to 7 clusters of flowers (racemes), each measuring less than 2 inches and positioned at nearly right angles to the stem. The flowers themselves are small, fleshy, and shaped like inverted cones with three lobes, emerging from the flower bud.

Effective management of Dallis grass primarily involves preventing the establishment of new plants. In residential gardens, the most effective control method is to remove young plants before they develop rhizomes or produce seeds. While mature plants can also be excavated, they may regrow if any rhizomes are left in the soil.

In terms of pests and diseases, the seed heads of Dallis grass are vulnerable to an ergot fungus known as Calviceps paspali, which can be harmful to livestock if consumed. This plant is recognized for its weedy and invasive characteristics.