LSU AgCenter's Weekly Message

To Manage Virginia Buttonweed, Start Now

When I was younger, we had a golden retriever that liked to graze on Virginia buttonweed. Eating of weeds by dogs is not a commonly given example of biological control, but my dad welcomed the help.

Not everyone has a weed-eating golden retriever, and unfortunately, this alone is not enough to adequately manage Virginia buttonweed, which is one of the top lawn weed issues in Louisiana.

One of the things that contributes to Virginia buttonweed being such a problem is the fact that it grows, flowers, and produces seed close to the ground. Also, the weed can root from broken stem pieces as well as spreading by seed. So, while mowing regularly and at the recommended height for a given turfgrass is enough to prevent a lot of weeds from producing seed [and thus from spreading], this doesn’t cut it for Virginia buttonweed.

Even though mowing at the appropriate height isn’t enough to control Virginia buttonweed, it’s worth repeating that good cultural practices – including maintaining soil pH in the optimum range, fertilizing at recommended times and rates, and mowing at an appropriate height for the turfgrass that you have – are the foundations of lawn weed management.

If you have Virginia buttonweed, though, some additional steps will be needed to get rid of it.

During April and May, as this weed is coming out of dormancy and new seedlings are growing from seed, herbicides containing 2,4-D; dicamba; and mecoprop/MCPP (or these three ingredients along with carfentrazone) can be used to spot-treat it in most warm-season turfgrasses, including centipedegrass, St. Augustinegrass, bermudagrass, and zoysiagrass. Examples of products that contain these ingredients include Bioadvanced Lawn Weed Killer, Compare-N-Save Weed Killer for Lawns, Fertilome Weed Free Zone, Fertilome Weed-Out Lawn Weed Killer, and Ortho Weed B Gon Lawn Weed Killer. (Some herbicide products have similar names but different ingredients, so check the active ingredients list before purchasing a product, and make sure it’s labeled for use on the type of turfgrass you have.)

It’s important to start spraying for Virginia buttonweed during the spring, since this is when the weed is more tender and susceptible to herbicides. However, herbicide applications will likely need to be continued into the summer to successfully manage it.

Herbicides with 2,4-D can injure some turfgrasses during hot weather. Once temperatures reach 85 degrees F, you can switch to either metsulfuron (e.g., MSM Turf or Manor) or the combination of thiencarbazone, iodosulfuron, and dicamba (Celsius). If the lawn has a large buttonweed population, it may be necessary to apply one of these products every four to six weeks.

When using any herbicide, be sure to read and follow label directions.

In the fall, after Virginia buttonweed has flowered and begun to produce seed, hand-removal is probably the most effective management option. Place the plants in a bag so that seed is contained and not allowed to fall back onto the lawn.

If you don’t feel like putting in the effort to get rid of Virginia buttonweed, you can comfort yourself with the fact that it’s native to Louisiana. It could be argued that it’s not a terrible-looking groundcover

during the warm part of year, but where it crowds out turfgrass, there won’t be much to see in the winter.

Let me know if you have questions.

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Dr. Mary Helen Ferguson is an Extension Agent with the LSU AgCenter, with horticulture responsibilities in Washington and Tangipahoa Parishes. Contact Mary Helen at mhferguson@agcenter.lsu.edu or 985-277-1850 (Hammond) or 985-839-7855 (Franklinton).