Garden Column for the Salisbury Post
Darrell Blackwelder
September 18, 2002

        I was pleasantly surprised last Saturday morning when I had about 20 people attend a fall lawn maintenance workshop. With the extreme drought last summer and the uncertainty of another drought this fall, I was skeptical anyone would show. However, we did have a good class with much discussion, especially about one particular weed that seems to dominate lawns in late summer and fall.
        Dallisgrass is a warm-season, grassy weed found throughout the United States, in hot summer areas from New Jersey to California. The weed was introduced and naturalized from Uruguay and Argentina and has taken permanent residence in Rowan County.
        The weed begins growth in late June and July. It grows best in moist areas and high-cut lawns fescue lawns which are the predominant Rowan County. The grass tolerates almost any type of soil, reproducing by seeds and rhizomes (underground stems).
        Dallisgrass has long coarse-textured leaves ½ inch wide and 4-10 inches long. Stems 2-6 inches long radiate from the center of the plant in a star pattern. Seeds are produced on 3-5 finger-like segments that grow from the top of these stems. These finger-like seed stalks are the most distinguishing trait of the weed, making well kept lawns unattractive. Plants form unsightly deep rooted clumps growing most vigorously in warm summer weather, but remains green into winter.
        Dallisgrass is often introduced into lawn areas with new turf grass seed or in some cases on sod. The seed can also be introduced on mowers that have been used in contaminated areas and then moved to weed-free sites. Cleaning a mower after mowing a contaminated site should reduce the chance of invasion into new areas. Try not to use soil from dallisgrass-contaminated areas to repair low or bare spots in the turf. Avoid aeration in the spring since seed tend to germinate on bare ground in the early summer.
        Non-selective herbicides such as glyphosate (Roundup) are the only practical method for controlling dallisgrass in late summer or early fall. Unfortunately, glyphosate kills both the dallisgrass and desirable turfgrass, leaving an area of dead turf. Sometimes the dallisgrass is not killed even though the grass itself is severely damaged or killed, so re-treatment a couple of weeks later is a real possibility. Treat as early as possible to stop Dallisgrass before it begins to develop seed heads and reproduce
        Selective post-emergence herbicides labeled to control crabgrass, dallisgrass and other warm season grassy weeds work only when the weeds are very small generally in late spring and early summer. Using these products now is a waste of time. Also, using these products often damage cool season turf in late summer.

Darrell Blackwelder is an agricultural agent in charge of horticulture with the North Carolina Cooperative Extension Service in Rowan County. For archived garden columns or other information, visit the Rowan County Master Gardener web site at www.rowanmastergardener.com or e mail Darrell_blackwelder@ncsu.edu

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