Foxtail grass is a common, invasive weed found across North America that quickly takes over lawns, gardens, and pastures, thriving in disturbed or thin turf areas. The primary concern is the danger posed by its mature seed heads, which are equipped with barbed, needle-sharp bristles called awns. These awns can burrow into the soft tissue of animals, causing severe pain, infection, and potential internal damage. Eliminating this persistent weed requires a comprehensive strategy incorporating physical removal, targeted chemical applications, and long-term turf health management.
Identification and Lifecycle of Foxtail Grass
Correct identification is the first step toward successful removal, as the foxtail grass family (Setaria) includes several common types, such as Green, Yellow, and Giant foxtail. Most problematic foxtails are summer annual grasses. They germinate in the spring, grow throughout the summer, produce seeds, and die off with the first frost in the fall. Yellow and Green foxtail seeds begin to germinate when soil temperatures reach approximately 65°F and continue to emerge throughout the early summer.
The distinguishing feature is the dense, bristly seed head, which often resembles a fox’s tail and contains the dangerous awns. Yellow foxtail has long, silky hairs found at the base of the leaf blade, while Giant foxtail has short hairs covering the entire upper surface. Control measures must be implemented before the plant reaches maturity and drops its seeds, typically between July and September.
Mechanical and Cultural Removal Strategies
Immediate, non-chemical control begins with physical removal, which is most effective when the plants are young and have not yet formed seed heads. Hand-pulling or digging is highly effective for small infestations, but the entire root system must be removed to prevent regrowth. This task is easiest when the soil is moist, allowing the fibrous roots to be lifted cleanly.
Mowing requires a specific approach to manage foxtail effectively. Standard mowing heights often encourage the plant to produce seeds lower to the ground, and mowing mature plants scatters seeds widely. To use mowing as a cultural control, maintain the turfgrass at the highest recommended height for the species. This encourages a dense canopy that shades out foxtail seedlings, which require full sun to thrive.
For small, heavily infested areas, solarization or smothering can kill weeds and seeds in the upper soil layer. This involves covering the area with clear or black plastic sheeting, tightly secured at the edges, for several weeks during the hottest part of the summer. The resulting high temperatures sterilize the soil surface and prevent light from reaching the plants, effectively addressing the soil seed bank without chemicals.
Targeted Chemical Control Methods
Chemical control is highly effective for larger foxtail infestations, especially when timed to interrupt the plant’s summer annual life cycle. The most effective strategy is using pre-emergent herbicides, applied to the soil before foxtail seeds germinate in the spring. These chemicals create a barrier that inhibits the root development of sprouting seeds, preventing them from establishing.
The application window for pre-emergent products, such as those containing prodiamine, pendimethalin, or dithiopyr, is generally when soil temperatures reach 55°F to 60°F for several consecutive days. Because foxtail seeds can remain viable in the soil for up to three years, a consistent, multi-year application is necessary to deplete the seed bank. This proactive approach prevents the problem before it becomes visible.
Once foxtail plants are actively growing, post-emergent herbicides are necessary, though they are less effective on mature plants with developed seed heads. Selective post-emergent products are formulated to kill weedy grasses like foxtail without harming the surrounding turf. These contain active ingredients such as quinclorac or fenoxaprop-p-ethyl. Non-selective herbicides, like glyphosate, kill all plant material they contact and should only be used for spot treatments or clearing areas like cracks in driveways or garden borders. Always consult the product label for specific application rates and safety precautions.
Long-Term Prevention and Turf Management
Achieving lasting foxtail control depends on creating an environment that actively discourages its germination and growth. Foxtail thrives in thin, damaged turf and bare soil because it is a poor competitor against healthy, dense grass. Improving the health and density of the desired turfgrass is paramount for long-term prevention.
This involves proper fertilization and aeration practices to ensure the soil provides the necessary nutrients and oxygen for deep turfgrass root growth. Overseeding thin areas in the fall or spring with desirable turf varieties increases the density of the lawn, effectively crowding out foxtail seedlings by blocking sunlight. Shallow, frequent watering favors the foxtail’s shallow root system; instead, practice deep, infrequent watering to encourage the turfgrass to develop deeper, more resilient roots that can better withstand dry periods.
In garden beds and ornamental areas, a thick layer of organic mulch, maintained at a depth of two to three inches, physically blocks sunlight and suppresses germination. Regular monitoring is an effective preventive measure, involving scouting the yard weekly for new seedlings, especially in disturbed or bare spots. Immediate hand-removal of young plants before they produce seed heads interrupts the foxtail life cycle and prevents re-seeding.