Sticker burr, also called grass bur or field sandbur, is an annoying weed that pops up in lawns and fields. It gets its name from a Greek term meaning armed with spines, because the burrs stick to clothing and can be painful when you step on one with your bare feet. Proper lawn care can help prevent these pesky weeds, but a herbicide may be needed after the sticker burrs take root.
1. Identifying Sticker Burr
Sticker burr seedlings are small and difficult to see, but have flat, hairless, sandpaper-like blades. The weeds are much more recognizable by the time they reach mature growth, when they sport burr seed heads, each one of which is really a capsule of one to three seeds. Sticker burrs can grow in all types of soils, but are best suited to dry, sandy soil. The weed germinates from late spring until the first hard frost or freeze occurs in the fall.
2. Natural, Non-herbicide Control
The most natural way to control sticker burr outbreaks is to prevent them through proper lawn maintenance. Set your mower as high as possible during the summer, because the added shade from taller grass is a deterrent to burr seeds. Avoid frequent light sprinkling, which simply encourages weed germination, and instead use an occasional deep-soak watering. Fertilize your lawn according to the specifications for its type, but in general, use a slow-release fertilizer twice a year.
3. Pre-emergent Treatment
Once sticker burr seedlings start to emerge, use a pre-emergent treatment, typically in late winter or early spring when the soil temperature reaches 52 degrees Fahrenheit. Most of these products contain the chemical oryzalin. Follow the label instructions carefully to avoid using too much, which can injure turf grass or other plants; a typical application for 1,000 square feet is 3 fluid ounces of oryzalin to 2 gallons of water, used in a herbicide sprayer.
4. Post-emergent Treatment
Once mature sticker burrs take hold, you will need a post-emergent herbicide. The most common is monosodium methanearsonate, better known as MSMA, MAMA or DSMA, and available from garden centers. For MSMA to be most effective, use it on wet grass after day temperatures are 75 degrees F, and broadcast a solution of 2 tablespoons MSMA per gallon of water. After the first use, apply the herbicide two more times, six weeks apart. Do not apply MSMA to newly seeded lawns until they have been mowed three times, and never use MSMA on St. Augustine or centipede lawns.
5. Safety Issues
Keep both pre-emergent and post-emergent herbicides out of the reach of children. MSMA is harmful if swallowed and may cause problems if inhaled or if it comes into contact with skin. If this should happen, call a poison control center or doctor for treatment advice. Wear protective clothing when handling and applying the chemicals, including long pants and long sleeves, gloves and boots. As a safety precaution, keep pets away from newly treated surfaces.
- Texas A&M AgriLife Extension: Grassbur
- Texas A&M AgriLife Extension: Weed of the Week: Grassbur
- Colorado State University Extension: Control of Annual Grassy Weeds in Lawns
- Texas A&M AgriLife Extension: Controlling Field Sandbur (Grassbur) in Turfgrass
- PBI Gordon Corporation: MSMA Herbicide Specimen Label
- Vegetation Manager: Oryzalin Pro
- Comstock Images/Comstock/Getty Images