Elimination of Dollar Weed - Knowledgebase Question

Myrtle Beach, So
Question by myrtlebsanto
May 25, 2010
We have a centipede lawn infested with dollar weed. Many products(granules and concentrates) including those with atrazine have been used. Dollar Weed flourishes, any suggestions?

Answer from NGA
May 25, 2010


The presence of dollarweed indicates that there is excessive moisture in the area. Research at the University of Florida demonstrated a reduction in dollarweed just by reducing irrigation frequency (http://gardeningsolutions.ifas...). Monitoring moisture levels and evaluating irrigation frequency are the first steps to controlling dollarweed. Landscape plants and lawns require one-inch of water a week for optimum growth.

Dollarweed thrives in weak, thin turf with excessive moisture. The first defense against dollarweed is to reduce moisture levels and modify cultural methods (i.e., proper mowing height and irrigation).  After taking steps to modify the lawn care techniques, a chemical control may still be necessary to further reduce the dollarweed population.

Atrazine (Hi-Yield Atrazine Weed Killer, Image for St. Augustine & Centipedegrass, Southern Ag Atrazine St. Augustine Weed Killer, and Spectracide Weed Stop for Lawns Conc. for St. Augustine & Centipede Lawns) can be applied to St. Augustinegrass and Centipedegrass up to two times a year. For maximum effect atrazine should be applied once in the fall and again in late spring (after spring green-up). Atrazine has a pre- and post-emergent effect on weeds, which means it helps to control both emerged weeds and weed seed.

If you've already tried and were unsuccessful with Atrazine, a three-way herbicide may be used safely on bermudagrass, zoysiagrass, centipedegrass, St. Augustinegrass and tall fescue. The active ingredients of a three-way herbicide include 2,4- D, dicamba, and MCPP (such as Ferti-lome Weed Out Lawn Weed Killer with Trimec?, Bayer Advanced Southern Weed Killer for Lawns, and Spectracide Weed Stop Weed Killer for Lawns). Herbicides containing 2,4-D should be applied at a reduced rate on St. Augustinegrass and centipedegrass to prevent damage to these lawns. If a second application is needed, apply the herbicide in spot treatments. Repeated applications of a three-way herbicide should be spaced according to label directions. CAUTION: Three-way herbicides should not be applied during spring transition (green-up of lawn) or when air temperatures exceed 90 ?F. A newly seeded lawn should be mowed a minimum of three times before applying a herbicide.

Or, Imazaquin (Image Nutsedge Killer) can be applied safely to bermudagrass, St. Augustinegrass, centipedegrass and zoysiagrass. Apply imazaquin in the spring (after spring green-up) when weeds are small. A second application can be made in six weeks after the initial application.

Choose one of the strategies and follow through with a second application. I'm sure you'll be successful.

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