Nothing designates spring’s arrival like walking barefoot on a lawn of lush, green grass. This pleasant experience can often turn into a painful, sticky situation with the presence of lawn burweed. Other names for this weed are spurweed and stinging grass. Lawn burweed (Soliva sessilis) is a winter annual that germinates throughout thin turf in the fall months as temperatures cool. It remains small and inconspicuous during the cold winter months. However, as temperatures warm in the early spring, lawn burweed initiates a period of rapid growth and begins to form spine-tipped burs in the leaf axils. The seed is contained within the hooked bur.
Lawn burweed is a low-growing, freely branched winter annual. It has opposite, sparsely hairy leaves that are twice divided into narrow segments or lobes. Maintain a healthy, dense lawn by fertilizing and liming according to soil test results and mowing at the proper height and frequency for your specific turfgrass. Healthy lawn grasses can out compete burweed for light, water and nutrients and reduce the level of infestation.
The key factor to effectively controlling lawn burweed is to apply a post-emergence herbicide during the winter months of December, January and February. The weed is smaller and easier to control during this time of year and has not yet developed the spine-tipped burs. Control is not impossible in March, April, and May, but the spines have already formed by this time and will remain after the weed dies. Because lawn burweed is a winter annual, it will begin to die in late spring as air temperatures reach 90 °F. Once the weed has reached a more mature state, multiple herbicide applications may be necessary which increases the potential for turfgrass injury. Dead or alive, lawn burweed poses a painful problem. The only solution to this is early identification and control.
A three-way herbicide may be used on bermudagrass and St. Augustinegrass. The active ingredients of a three-way herbicide often include the following broadleaf weed killers: 2,4-D, dicamba, and mecoprop (MCPP). Examples of a three-way herbicide are Ferti-lome Weed-Out Lawn Weed Killer with Trimec®, Bayer Advanced Southern Weed Killer for Lawns, Spectracide Weed Stop Weed Killer for Lawns, and Southern Ag Lawn Weed Killer with Trimec®.
Isoxaben is a pre-emergence herbicide for control of lawn burweed, as well as many winter broadleaf weeds in bermudagrass and St. Augustinegrass. Apply isoxaben in late September to early October before the winter weeds germinate. Do not reseed or overseed within 60 days of application, and do not apply to newly seeded lawns until the lawn has been mowed three times. An example of a home lawn granular product containing isoxaben is Green Light Portrait Broadleaf Weed Preventer. Granular pre-emergence herbicides must be activated by ½ inch of rainfall or irrigation.