Grass burrs prefer soils with a lack of moisture and because the weeds grow in sandy areas, some refer to them as sand burrs. The outside shell has spiny marks that attach to clothing, animal fur and human hair. The burrs also attach to skin and may cause some amount of pain. Herbicides containing certain types of chemicals are the best method of eradicating the problem.
According to Texas A&M's Aggie Horticulture website, the best method of killing grass burrs is a combination of herbicides and fertilizers. The site recommends pre-emergence chemicals, which kill the burrs before the weeds appear on the surface of the grass. If the grass burrs already appeared, then apply the mixture after a rainstorm or lightly spray the weeds. The weeds absorb the chemicals when absorbing water. Using a combination of herbicides and fertilizers increases the amount of chemicals absorbed by the burrs.
Use a product that contains 2,4-D for killing of any weeds, including grass burrs. Aggie Horticulture also recommends the chemicals pendimethalin, benefin and oryzalin. Pendimethalin is the common chemical name for the brand name herbicide PreM, which the company Lesco manufacturers. The company Green Light is behind the chemical benefin and sells the chemical under the name Amaze Grass & Weed Preventer. Lilly Miller, Lawn & Garden Products and Southern Ag. all sell products containing oryzalin. Products containing oryzalin include Weed Stopper, Surflan and Weed & Grass Preventer. You may need multiple applications before seeing results.
Even after you kill the weeds, the small burrs remain in your yard. Wear long pants and a long-sleeved shirt. Cover your hands with gloves, keeping the burrs from sticking to your skin. Carefully rake the area with a metal rake, catching the burrs inside the metal prongs. Transfer the burrs to a trash bag and dispose of the burrs. Keep any children or animals away from the area while spraying the chemicals on the weeds, as the burrs attach to nearly anything they touch.
Using the Chemicals
For powdered chemicals or crystals spread the herbicide on the weeds with a specialized garden sprayer. Spread half the herbicide across the weeds, moving from the top of the patch down to the bottom. Wait a few minutes and go over the weed patch a second time with more herbicide, moving from left to right. The multiple directions ensure that you cover all of the weeds and kill all of the grass burrs.