Lawn burweed is a winter annual weed that becomes problematic in spring. It is a low growing weed in lawns with leaves somewhat resembling a miniature version of parsley.
If you had a problem with this weed and missed the narrow window to apply a preemergence herbicide back in October, you still have an opportunity to control it now with a postemergence herbicide before the prickly burs form. But you need to act soon.
Look for the very low growing green burweed plants almost hiding out in your lawn now in those areas where it was a problem last February/March. Look carefully because it will be growing very close to the ground. It does not have the burs now. So it will not be painful to walk on or to touch, yet.
Burweed seeds germinate in fall. The plant remains small and inconspicuous during winter. It’s not until temperatures warm in spring that this innocent looking and often unnoticed weed begins to rapidly grow, forming spine-tipped burs in its leaf axils.
These sharp, spiny burs hurt as children begin to use the yard again, running barefoot on an early spring day. Even the dog playing fetch suddenly starts doing a painful dance as it finds its way into a prickly patch of burweed. This weed can make a lawn area completely useless until it dies away and decomposes in late spring or early summer, only to reappear from left behind seeds next winter. Individual plants can form a mat spreading to a foot or more in diameter.
This weed can be easily controlled during winter months before spiny burs become a problem and before seeds are produced. But if you wait, you’ll have to put up with the pain and inconvenience until the burs again wither away. This can become an endless and unnecessary cycle. You can break this cycle and eliminate this weed by controlling it before the burs develop.
December, January and early February are ideal months to apply an herbicide for the control of burweed. Look for lawn herbicides containing, atrazine, 2,4-D or dicamba. Centipedegrass and St. Augustinegrass have excellent tolerance of atrazine. Although labeled for use on most of our permanent lawn species, dicamba and 2,4-D herbicides can injure centipedegrass and St. Augustinegrass, especially during periods of hot weather. Use lower rates of these herbicides on centipede and St. Augustine lawns. Do not use these herbicides within the root zone of desirable plants, especially dicamba. Always follow label instructions and precautions.
The key to controlling lawn burweed is to apply an appropriate herbicide during the winter months.
Larry Williams, UF/IFAS Extension Agent, Okaloosa County, January 4, 2017
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