Lawn & Garden
AUBURN UNIVERSITY, Ala. – The most wonderful time of the year is here. Holiday wishes, good food and – burweed? The prickly weed makes its appearance during the winter. Not only is it unattractive, but it can cause unpleasant encounters. Shane Harris, the Alabama Cooperative Extension System county coordinator for Tallapoosa County, said people really don’t notice this weed until they actually step on it. Don’t let burweed put a damper on the holiday spirit; take control before it’s too late.
Lawn burweed (Solvia sessilis) is a common winter annual plant. This means that the plant grows in the winter, then flowers and makes seeds in the late winter and early spring. Burweed becomes a major problem when it begins to grow seed. The seeds are encapsulated by small burs with sharp spines on them.
Alabama Extension Turfgrass Specialist David Han describes the spurs as “something much smaller, yet much more painful and annoying to step on, than the gumballs from a sweetgum tree.”
The spiny burs are the fruit of the plant. Once a burweed plant make the burs, they will be present in the lawn for a while. Even if homeowners manage to kill the burweed at this stage with a herbicide, the dead burs will remain. Their resilience quickly becomes a nuisance to homeowners.
Burweed is difficult to eradicate completely, however steps can be taken to discourage its growth. Since lawn burweed is a winter plant, it grows when warm lawns are dormant and thin. Therefore, it is important to keep a lawn in good shape going into the winter.
Factors that can thin out a lawn—including too much shade, soil problems (compaction, improper pH or improper watering) or improper fertilization—will accelerate burweed growth. Unfortunately, burweed is impossible to avoid completely. According to Han, the seeds are numerous and easily spread by water or animals. It is often more of a problem after wet winters because of the excess rains that help spread the seeds.
“The key is to either prevent lawn burweed seeds from coming up in the fall with a pre-emergent herbicide or killing emerged burweed plants before they start to flower,” Han said. “In most of Alabama, this means to kill them in December or early January.”
Pre-emergent herbicides should be used during October or November. These herbicides are marketed as weed preventers in stores. This application will prevent the seeds from coming up in the first place. As an alternative, there are several post-emergence herbicides (marketed as weed killers) that can be used in December or early January. The key is to kill the burweed before they produce the spiny fruits. Han says almost all commercially-available lawn weed killers should successfully remove it.
According to Harris, waiting until the spring to control burweed will allow for the burs to form. At this stage, it is already too late to control. In December or January, scan through the lawn to check for the plant. They will be small in December, so it must be an active search. If any weeds are found, use a broadleaf weed killer.
Make sure the only thing spreading this holiday season is joy and cheer, not lawn burweed. For more information about lawn burweed control, check out the video from Harris below. People can also visit the Alabama Extension website, www.aces.edu, to contact the home grounds, gardens and home pests agent in their area for additional assistance.