Sticker burrs, commonly known as sandbur (Cenchrus species) or puncture vine (Tribulus terrestris), are weeds that inflict pain and spread aggressively. These plants produce hard, spiny seed pods that readily attach to clothing, shoes, animal fur, and tires. The seeds within these burrs can remain viable in the soil for several years, making eradication a challenging, multi-year process. Effective control requires a comprehensive approach that targets the plant at every stage of its life cycle. This guide details the physical and chemical methods available to eliminate these invaders and prevent their return.
Non-Chemical Removal Techniques
For small infestations or in areas where chemical use is a concern, physical removal remains a viable option. Manual removal involves pulling or digging the plants out of the ground, which is most effective when the soil is moist and the plants are young, before they develop mature burrs. It is important to wear heavy-duty gloves to protect hands from the painful spines and to ensure the entire root system is removed.
Solarization treats larger, non-turf areas by harnessing the sun’s energy to heat the soil to lethal temperatures. This involves covering the infested area with clear plastic sheeting for several weeks during the hottest part of the summer, effectively killing plants and dormant seeds in the topsoil. Shallow tilling, about one inch deep, can also disrupt young seedlings. Avoid deeper tilling, which can inadvertently bury dormant seeds and allow them to germinate later.
Mowing is largely ineffective for puncture vine due to its low-growing habit, but it can manage sandbur. If mowing sandbur, use a bagger attachment to collect and dispose of clippings and loose burrs, preventing spread. All removed plant material or collected burrs should be disposed of in the trash, never in a compost pile, as the seeds can survive.
Selecting Effective Herbicides
The most efficient strategy for controlling widespread sticker burr infestations often involves the strategic use of herbicides, categorized by when they are applied. Pre-emergent herbicides are applied before seeds germinate, creating a chemical barrier in the topsoil. These chemicals inhibit cell division in newly sprouted seedling roots, preventing them from establishing a functioning root system.
Common active ingredients effective as pre-emergents against sandbur include dithiopyr, pendimethalin, and isoxaben. For puncture vine, products containing oryzalin, trifluralin, or benefin can provide partial control. The effectiveness of any pre-emergent is dependent on the application timing and a uniform barrier.
Once weeds are actively growing, post-emergent herbicides are necessary to kill established plants. For the broadleaf puncture vine, products containing 2,4-D, dicamba, or a three-way combination herbicide are generally effective. Sandbur, a grass, is more difficult to control with retail products, but specialized post-emergents containing imazaquin or MSMA can be used (MSMA availability is restricted in many areas). These chemicals are absorbed by the foliage and translocated throughout the plant.
Optimizing Treatment Timing and Application
The timing of herbicide application is important for successful control. For summer annual weeds like sandbur and puncture vine, pre-emergent herbicides must be applied in early spring before soil temperatures consistently reach 55 degrees Fahrenheit, the trigger for germination. A second application is often recommended six to ten weeks later to maintain the chemical barrier.
Pre-emergent products must be activated by moisture, requiring about a half-inch of water from rain or irrigation shortly after application to create the necessary barrier. Applying these products too late, after germination, renders them ineffective. Using a soil thermometer to monitor temperatures at a one-to-two-inch depth provides a more reliable timing guide than relying solely on calendar dates.
Post-emergent chemicals are most effective when applied to young, actively growing plants, ideally before burrs start to form. Once spiny burrs mature, killing the parent plant will not prevent the burrs from hardening and dispersing seeds. Follow label instructions precisely, especially regarding temperature restrictions, as high heat can increase the risk of damage to desirable turfgrass.
Long-Term Prevention Strategies
Long-term control shifts the focus from direct eradication to cultural practices that discourage weed establishment. A dense, healthy lawn is the most effective defense against sandbur and puncture vine, as turfgrass crowds out weed seedlings and limits the bare soil they prefer. Improving soil health through aeration, proper fertilization, and consistent watering encourages a thick stand of grass that naturally suppresses weed growth.
Proper mowing practices also contribute to prevention by keeping the lawn tall enough to shade the soil, which inhibits weed seed germination. Cut grass at the highest setting recommended for the turf type, avoiding removal of more than one-third of the blade height in a single mowing. Continual monitoring of previously infested areas is necessary, as the seeds can remain dormant for years, requiring persistent vigilance and maintenance applications of pre-emergent herbicides.