Every year at the end of the summer, I get calls from homeowners asking how to get rid of sandspurs in their yard. Sandspur is an annual warm-season weed that masquerades as grass until the end of the summer when it flowers and sets seed, which is a prickly spur. The spurs are extremely painful to step on, and can even be a problem for pets when they get spurs in their fur or paw.
Because sandspurs blend in so well with the lawn, most people don’t know even know they are there until that first painful realization. That’s when I start getting the phone calls, as homeowners try to find a weed killer that can take out that nasty weed. Unfortunately, by this time of year, it’s just too late. For just about any annual weed, not just sandspurs, by the time the weed is at maturity — flowering and setting seed — there is no miracle herbicide that will kill it.
So what is a homeowner who likes to walk barefoot in the lawn to do? The first step in controlling this weed is to maintain healthy turfgrass with proper fertility and watering. Information about how to maintain your turfgrass optimally may be found at the Richmond County Cooperative Extension office. Take a soil sample to be sure your soil pH and fertility is where it needs to be for optimum turfgrass growth.
With an understanding of proper timing, herbicides can be effective. Pre-emergent herbicides (which prevent seeds from developing) are often the treatment of choice for weeds, but in this case, they are not the most effective. The sandspur’s large seed makes it a challenge to control with pre-emergents.
However, pre-emergent herbicides with the active ingredient (or “ai”) pendimethalin or oryzalin may provide partial control. Apply in early spring according to label directions. Both are safe for turfgrasses common in our area, including centipede, Bermuda grass and zoysia. The most effective approach is the use of a timely post-emergent herbicide treatment.
In late May or June, when sandspurs are a few inches high and actively growing, and after lawns green up, apply a post-emergent herbicide with the active ingredient imazaquin, which is safe for Bermuda, centipede and zoysia grass.
For those with centipede grass, sandspur is one weed that is easy to kill in that herbicide-sensitive turfgrass. Look for a herbicide with the ai sethoxydim, which is very effective on sandspurs (and, by the way, bahia grass) and is labeled for centipede grass only. Do not use on Bermuda grass — it will kill it. Remember, always read and follow label directions when using any pesticide.
If you miss the window of opportunity to treat sandspur with herbicides, remember it is an annual weed. That means it completes a life cycle all within one growing season: growing from seed, flowering, setting seed and dying between spring and fall. A big part of the weed control battle is to prevent the plant from setting seed to grow next year, which can be done by removing the seed.
Mow at a very low height with a bagger to capture and remove seeds. You could even try dragging an old blanket or towel over the weeds. The fabric will capture a number of seeds, and then can be thrown away. By removing the developing seeds, you are reducing the number of seeds that will develop into plants next year.
For information about managing weeds in your lawn and proper turfgrass management, contact the Richmond County Cooperative Extension office at 997-8255.
Paige Burns is assistant horticulture agent for the N.C. Cooperative Extension’s Richmond County extension office.