Goat head stickers, also known as Puncture Vine (Tribulus terrestris), is an aggressive summer annual weed that poses a serious problem for yards and public spaces. The plant’s most infamous feature is its woody, spiky seedpod, which splits into segments with sharp spines capable of puncturing bicycle tires, thin shoes, and injuring people and pets. Tribulus terrestris is a prolific seeder, producing hundreds of burs that can remain viable in the soil for up to seven years, creating a massive seed bank. This low-growing plant forms dense mats that choke out desirable vegetation and thrives in disturbed, hot, and dry environments. Dealing with this pest requires a combined approach of immediate physical removal, chemical control of active plants, and long-term prevention.
Immediate Physical Removal and Safe Disposal
The first line of defense against a goat head infestation is physically removing the existing plants, a method most effective for small or newly established patches. Manual removal is easiest when the soil is moist, which helps ensure the entire taproot is extracted. Since Tribulus terrestris is a prostrate plant, growing low to the ground, failing to remove the deep taproot often allows the plant to quickly regrow.
Wear thick, protective gloves and sturdy footwear to avoid the painful stickers. Specialized weeding tools, like a narrow trowel or weed wrench, can help you cleanly sever the taproot well below the soil surface. Focus your effort on removing plants before they develop yellow flowers or mature into the hard, spiny burs, which can happen within a few weeks of sprouting.
Proper disposal is paramount to preventing the immediate spread of the weed. Never compost the pulled plants, as the seeds within the burs can easily survive the low heat of a typical backyard compost pile and be redistributed later. Place all plant material, especially the spiky burs, into heavy-duty plastic bags. Sealing the bags and leaving them in direct sunlight for several weeks—a process called solarization—will generate intense heat to sterilize the seeds before disposing of the material with your regular trash.
Targeting Active Plants with Post-Emergent Herbicides
For larger infestations where manual removal is impractical, post-emergent herbicides are necessary to kill established, actively growing plants. These chemicals are designed to be absorbed by the foliage to kill the weed after it has emerged from the soil. The most effective selective herbicides for Tribulus terrestris typically contain active ingredients such as 2,4-D, dicamba, or a combination of broadleaf weed killers.
Apply these systemic products when the plants are young, actively growing, and ideally before they have flowered and set seed. Young plants are more susceptible to the chemical, allowing for better translocation of the herbicide throughout the plant and into the taproot. If the plants are already mature and producing seeds, a non-selective herbicide like glyphosate may be used, but extreme care must be taken to avoid drift onto desirable plants.
Due to the weed’s rapid growth cycle and tendency to sprout in waves, a single application is rarely enough to achieve complete control. Plan for repeat applications, often spaced ten to fourteen days apart, to target any plants that were missed or that sprout shortly after the initial treatment. Always follow the product label carefully for application rates and safety precautions to maximize effectiveness and minimize risk to the surrounding environment.
Stopping Future Growth with Pre-Emergent Strategies
The long-term battle against goat head stickers hinges on preventing the existing seed bank from germinating. Pre-emergent herbicides work by creating a chemical barrier near the soil surface, killing the seeds as they begin to sprout. This strategy is considered the most effective for breaking the weed’s persistent cycle.
Timing the application is important, as the chemical barrier must be in place before the seeds begin to germinate, which typically occurs when soil temperatures consistently reach 60°F. In most regions, this means applying the pre-emergent in late winter or early spring. Specific effective products contain active ingredients such as trifluralin or pendimethalin.
Ensure the pre-emergent product is activated by water, either through irrigation or rainfall, shortly after application to move the chemical into the top layer of soil where the seeds reside. Because the chemical barrier degrades over time, a second application in mid-summer is often recommended in warmer climates to maintain protection. Supplementing chemical control with cultural practices, such as maintaining a dense, healthy turfgrass, can also suppress germination by shading the soil and limiting available space for the weed to establish.