Lawn & Garden
AUBURN UNIVERSITY, Ala. – While winter brings holidays and many times of happiness, it also brings with it one of the biggest lawn nuisances; burweed. This prickly weed is not only unattractive, but it can also make for some unpleasant encounters. There are several things homeowners can do to ensure that burweed doesn’t put damper on their season of joy and cheer.
What is Burweed?
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. The main issue with lawn burweed is when it grows seed. These seeds are encapsulated by small burs with sharp spines on them.
David Han, an Alabama Cooperative Extension System home grounds, gardens and home pests specialist, 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 plant makes the burs, they will be present in the lawn for a while. Even if people manage to kill the plants with an herbicide at this stage, the dead burs will remain, which makes them such a pain to homeowners.
Since lawn burweed is a winter plant, it grows when warm season lawns are dormant and thin. This means that 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. Burweed is often more of a problem after wet winters because the excess rains help further 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.”
If controlling with a pre-emergent herbicide, this should be done in 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 a second option, there are several post-emergence herbicides (marketed as weed killers) that people can use in December or early January. The key is to kill the plants before they produce the spiny fruits. Overall, Han said almost all of the commercially available lawn weed killers should successfully remove lawn burweed.
According to Han, a lot of people don’t notice lawn burweed until they step on the burs. At this stage, it is really too late to control. He recommends looking through the lawn in December or January. If any plants are found, use a broadleaf weed killer. The plants will be fairly small in December, so people will have to actively search for them.
For more information about lawn burweed or other lawn care information, visit the Alabama Extension website at www.aces.edu. People can also contact the home grounds, gardens and home pests agent responsible for their area.