A prickly weed is making its presence known in area lawns. When first detected, many people initially think they have sandspur, a summer annual grassy weed that is common in sandy soils. Thorny spines in lawns this time of the year, though, are caused by quite a different plant.
Lawn burrweed, also known as spurweed (Soliva sessilis), has become a common turf weed in our area that is easily identified by its sharp, spiny seed pods, which ripen in late spring. This weed has actually been growing inconspicuously all winter, and dies with the onset of warm weather. Unfortunately, it leaves behind a crop of seeds that will lie dormant through the summer, waiting for the cooler temperatures of fall to start growing new plants and continue the cycle next year.
Lawn burrweed is one of many common annual cool season weeds that grow in area lawns. As they grow larger and start to flower and set seed, there is little that can be done to control them. This weed also readily adapts to mowing by growing very low to the ground, and is still able to flower and set seed even when frequently mown.
While burr medic can be controlled with regular mowing, this will not kill the weed. It is also tolerant of most herbicides, though non-selective types can help kill the plant as well as boiling water. Neither of these, however, will kill the burrs that are left behind in the lawn or garden.
Burr medic germinates in fall and winter, and flowers in spring.
Since burr medic spreads and reproduces by seed, the best way to control the weed is to remove it before it has a chance to set its seed, even better before it flowers.
Types of Burr Weeds
If your lawn is filled with prickly burrs, you likely have burr weeds. With a little vigilance, however, it is possible to control burr medic and improve the health of your lawn. Read on to learn more.
Burr medic (Medicago polymorpha), also known as burr weed, is a type of trifoliate weed that can quickly spread throughout the lawn and garden if not controlled.
You can recognize this weed by its green serrated leaves and reddish purple colored stems that creep closely along the ground. It also has small yellow flowers. After flowering, the tiny green pods produce prickly burrs. These will eventually dry up and turn brown, spreading seeds everywhere.
There are several types of burr weeds, most of which can be found growing in a wide range of conditions and soil types. However, burr medic seems to favor poor soils, such as heavy clay. Like other trifoliate weeds, such as clover, burr weed has leaves that are grouped together in threes.