Goat head weed (Tribulus terrestris) is an annual plant notorious for its aggressive spread and painful, spiky burrs. These hard burrs contain the seeds and are easily dispersed by attaching to tires, shoes, and animal fur. Eradication is a multi-year effort because the seeds can remain viable in the soil, forming an extensive seed bank that continues to sprout for up to seven to ten years. A successful strategy requires immediate physical removal combined with targeted chemical control to prevent the current generation from producing new seeds.
Manual Removal and Immediate Cleanup
Immediate physical removal of existing goat head weeds is foundational, especially before the plants produce mature burrs. These weeds develop a deep taproot, so removal is easiest when the soil is moist and the plants are young. Tools like a stirrup hoe or a specialized weed puller can help sever the taproot beneath the soil surface, ensuring the entire plant is extracted. For smaller infestations, wear thick, puncture-resistant gloves to hand-pull the weeds and protect against the sharp spines.
Once removed, the plants and any existing burrs must be carefully collected and disposed of to prevent reseeding. Avoid placing pulled weeds into a home compost pile, as the burrs can survive the composting process. Instead, seal all plant material, especially the burrs, securely in thick plastic bags and dispose of them with household trash. For immediate cleanup of existing burrs, dragging an old carpet piece or a specialized burr roller across the infested area is effective, as the spines will snag onto the material.
Applying Post-Emergent Herbicides
Post-emergent herbicides kill weeds that have already sprouted and are actively growing. The most effective time to apply these chemicals is when goat head weeds are young seedlings, before they develop flowers or burrs. Once hard burrs form, the plant’s focus shifts to seed production, and the effectiveness of chemical treatments is reduced. Post-emergent sprays work best when temperatures are between 65 and 85 degrees Fahrenheit, and the plants are actively metabolizing the chemical.
For widespread infestations without desirable turf, a non-selective herbicide containing glyphosate can be highly effective, though it will kill any plant it contacts. In lawn or garden settings requiring selective control, herbicides containing 2,4-D, dicamba, or a combination of both are the preferred options. These selective broadleaf herbicides mimic the plant’s growth hormones, causing uncontrolled cell division. Always follow the product label instructions precisely for application rates and safety precautions, including wearing personal protective equipment and avoiding application on windy days.
Strategies for Long-Term Eradication
Lasting eradication relies on breaking the weed’s life cycle by targeting the extensive seed bank in the soil. This requires a multi-year strategy centered on pre-emergent herbicides and cultural controls. Pre-emergent herbicides are chemical barriers applied to the soil before the seeds sprout, preventing germination rather than killing an established plant. They are effective only against new seedlings, not existing weeds.
The timing of the pre-emergent application is paramount, as it must be applied just before the soil warms enough for the seeds to germinate. For this summer annual weed, the application window typically opens in early spring when the top two inches of soil reach a consistent temperature of 50 to 55 degrees Fahrenheit. Active ingredients like trifluralin or prodiamine are commonly used, forming a chemical shield that disrupts the seedling’s initial root development. A fall application may also be beneficial in warmer climates to catch late-season germination.
Integrating cultural controls further suppresses the seed bank and creates an environment less favorable to the weed.
Cultural Control Methods
- Establishing a dense, competitive ground cover, such as a healthy turfgrass lawn, can choke out new seedlings by blocking sunlight and competing for soil moisture.
- Mulching garden beds and non-turf areas with a thick layer of organic material or landscape fabric can physically prevent the seeds from receiving the light they need to sprout.
- In small, non-vegetated areas, soil solarization involves covering the soil with clear plastic sheeting during the hottest months. This heats the soil to temperatures lethal to the dormant seeds.