Burweed and sandspurs: The bane of barefoot strolls through the grass

Imagine you are walking barefoot, peacefully through the grass in your backyard. Your feet lightly tread on the soft green turf and the grass blades are tickling you softly between the toes. All of a sudden, you step on something sharp and hard, and your once-delicate stroll ends with you screaming out in pain. You’ve just stepped on a burweed. Or maybe you call them spurweed. Either way, you’ve stepped on a cool season annual broadleaf weed that produces a hard-coated spiny seed, and boy does it hurt. Now for the bad news.

Once burweed has matured to the point of producing seeds, it’s very difficult to control. As a cool-season annual, burweed has been growing in your lawn since sometime last fall, but you haven’t noticed it until now. The good news is that the plants will die as the weather warms up, but those prickly seeds will stay in the lawn for a good while. Herbicides containing 2,4-D might kill the plants a little quicker, but they won’t get rid of the seeds. If the plants are contained in a relatively small area in the yard, you may be able to remove a good amount of the seeds by doing a thorough hard-raking of that area.

Right: Burweed fruit. Hard-coated, spiny, and all-too-present in our lawns, these plants will put an end to a barefoot stroll through the grass in any backyard. Photo: H. Rose, CC BY 2.0

Above left: A burweed clump, about the size of the palm of a hand. It looks innocuous, but its effect is anything but. Photo: H. Rose, CC BY 2.0 Above right: Burs. The burs blend in well with the ground, causing untold misery to anyone walking barefoot and unaware of what lurks in the lawn. Photo: M. Lavin, CC-BY-SA 2.0

The best control against burweed is preventative – using pre-emergent controls that stop the weed before it comes up. Many of the same pre-emergent herbicides commonly used in the spring time to control summer annual weeds such as crabgrass can be used in the fall for weeds like burweed.  Remember this in the fall to stop next year’s plants. 2,4-D can also be used during warm periods in late winter and early spring before the spines form. Lawns with centipede grass should avoid 2,4-D other than at very low doses, as it can cause harm to centipede, and instead use products containing certain formulas of the chemical carfentrazone, such as Quicksilver and Speedzone.

At the risk of being confusing, there is a similar weed that comes out during summer called sandspur. This weed also forms a hard, spiny seed that will make you shout naughty words if you step on it.  he difference in terms of control is partly recognizing the time of year the weed is actively growing, but also knowing that sandbur is a grassy weed, whereas burweed is a broadleaf weed. That means the chemical options are different. For grassy weeds, post-emergent control is very difficult because nearly any product that will kill the weed will also harm or kill the turf it is growing in. Pre-emergent controls are generally the best option for grassy weeds like sandbur, and unfortunately, it’s now a bit too late for that this year.

Heavy infestations of burweed or sandspurs in lawns are usually indications of poor grass stands and low-quality soils. While herbicides may help temporarily, you’ll need to take some other measures to strengthen the lawn for better long-term control. Visit www.turffiles.ncsu.edu to view a maintenance calendar specific to the type of grass you are growing, or visit the extension office and ask for a publication called Carolina Lawns. Either option will give you lots of helpful information about how to care for your lawn so that you are less likely to deal with problems like burweed and sandspurs.

Matthew Stevens is the County Extension Director and Horticulture Agent for North Carolina Cooperative Extension’s Pitt County Center.  If you have questions about this article or gardening in general, please contact the Pitt County Extension Master Gardeners at [email protected] or 252-902-1705.