Origin:
Native to South America, now common throughout the southwest United States.
Biology:
A perennial grass weed that reproduces only from seed. Where regular tillage is done this is not an important weed pest, but it is common in turf, alfalfa hay fields, and in agricultural sites that are not regularly tilled. Seeds are capable of germinating throughout the year, but in cultivated crops germination seems to be primarily in mid to late spring, with plants maturing in late summer to early fall.
Identification:
Mature plants can grow as tall as 4 to 5 feet. Stems have 2 to 6 nodes, and may recline or grow upward. Leaf blades are flat, about ½ inch wide, and 2 to 6 inches long. Leaves are generally hairless, and where the leaf attaches to the stem the sheath is somewhat loose. Flower heads arise off of a stem that is up to 16 inches long, and consist of 3 to 5 branches that are up to 4 inches long. Each branch, or spikelet, contains the flowers, and these are arranged in a dense group along only one side of the branch.
Characteristicts Important to Control:
A perennial weed that grows only from seed. Tillage will reduce populations of Dallisgrass.
