It’s now the season to take barefoot walks in the yard. In many cases that can be painful due to a tiny lawn pest called spurweed. It has a lacy almost fernlike appearance and it is often less than an inch tall. However, there can be a lot of ouch in that inch.
Spurweed begins its growth in late winter. It can develop a rather strong foothold in warm-season turf like Bermuda grass, St. Augustine and centipede grass. These grasses are brown and dormant in cold weather, so the spurweed has little competition. In cool season turf like fescue or ryegrass it usually has more trouble competing for light, so it’s often a smaller problem.
When young, spurweed has delicate leaves and stems. They are deeply divided, hairy, soft and emerge from stems in pairs. The real problem comes when this plant sets fruit. These tiny cone-like fruits are barbed and spiny, and the nasty little structures provide seed for next year’s crop.
At this point spurweed control will have to wait until the coming fall when new plants emerge. Once seeds mature, killing the plants has no lasting effect. Once warm weather hits for good they will die anyway, but the little burrs will still be there.
We are reaching the critical time. Some spurweed has matured already, but we can still weaken next year’s problems if we act quickly. There are a few natural products available which will kill spurweed in actively growing perennial turf, but they will injure the grass temporarily.
These products work by destroying the plant’s ability to retain water. They dissolve the waxy protective leaf coating, so they kill what they hit. Perennial grasses will send out new shoots and recover quickly. The spurweed and any annual weeds will die. The nice thing about these chemicals is that they have very low toxicity to animals.
More traditional broad leaf herbicides like 2,4-D, dicamba or MCPP can cause longer term turf damage, especially to sensitive grasses like St. Augustine or centipede. These chemicals should have been applied earlier in the season when the turf was dormant. Always apply chemicals on calm days to prevent hitting non-target areas. Also, most herbicides work better on warm days, so keep that in mind too.
In fall you can attack this weed with pre-emergent chemicals. They work by preventing seeds from germinating. When used properly they do no damage to established turf. Many of these are applied in granular form, so there is less risk of herbicide drift to nearby places.
You can also use triazine herbicides like atrazine in the fall on warm-season turf. However, these chemicals will kill cool-season grasses. Non-selective chemicals like Round-up will kill spurweed, but they will also kill actively growing turf be it warm or cool-season.
Once you’re rid of this pest, the best defense is a healthy thick lawn. To achieve this, don’t mow too close, use a sharp mower and mow often. Never remove more than a third of the canopy at one time.
What are natural alternatives to kill the spur weed?
Ted Manzer teaches agriculture at Northeastern High School.
The only natural methods I’ve used with positive results are more preventative than eradication. Keeping a thick healthy turf by proper mowing and fertilization can prevent it from becoming a problem, but it takes a long time to choke it out. Don’t ever let your lawn get long and mow frequently. Eventually it will thicken up and the spurweed can’t compete. It might take a coupe years though.
Either full sun or partial shade in stressed, worn, or bare areas of turfgrass is where it grows best reaching height of 2 inches and a spread of 6 inches. It is known for its tiny sharp-needled seeds and small feathery leaves that have the appearance of parsley. The seeds are contained in a pod that appears in the junction of branches and they can hook onto clothing, shoes or other equipment and travel great distances. The plant develops a number of creeping stems that produce shoots that, if left alone, will form a low ground cover. When the plant matures, it displays small, bright yellow flowers. In some areas of the country, the plants is known as Bindi Patches with the reputation that they cannot be walked on barefoot. This includes dogs and cats, which tend to avoid sites where the weed appears.
Lawn burweed, is one of nine species of the Burweed genus in the Asteraceae (daisy) family. It is a small, low, fast-growing, herbaceous, broadleaf annual, typically seen in winter, growing in lawns. It is listed as a noxious weed in 46 states.
Healthy turfgrass is one of its biggest competitors. Manually remove the weeds by pulling up the plant including the root; however, this should be done before seeding. Because of its prostrate growth habit it is very difficult to mow it. Manage with herbicides that target broadleaf plants. Aerating the soil also tends to reduce the presence of lawn burweed.