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Most of us can easily identify the seed heads of foxtails in tall grasses or prairie areas. If you are outdoors anytime in late summer/early autumn, you can see these distinctive grasses growing in open areas. Setaria viridis, or more specifically, green foxtail, exists in many regions of the United States, and while it looks like something that is visibly pleasing and inviting to touch, the seed heads of the green foxtail can cause extensive damage to turf, lawns, pastures, and even livestock living within pastures.

Green Foxtail History

The tufted tops of the grass are synonymous with early autumn in most parts of the country. However, the green foxtail is not originally indigenous to the United States. It is thought to have been introduced from Europe as an accidental contaminant in seed crops being sent to the United States aboard ships.


There are several types of foxtail that are found within the United States. Green foxtail can be identified by its 1-4 foot tall leaves, often growing in clumps. Its root systems often become matted because of tillering at lower stems or nodes. Stems are smooth and hollow, with smooth upper surfaces of mature leaf blades varying from smooth to sparsely hairy. The most prominent identifying feature is the seed head, which resembles a fox’s tail. The seed head is fuzzy and tapered and can range in size from 1-5 inches long and about half an inch wide. The seed head looks soft and inviting, but individual hairs are barbed at the ends.

Green Foxtail - Setaria viridis pic 2

Green Foxtail Pic 3

Locations of Green Foxtail

The weed is found in most regions of the country but is most prevalent in areas where temperatures are moderate. Hot summers and cold winters are the most conducive environment for the grassy weed. Areas with loose or sandy soil, pastures, prairie, grasslands, or soil with a lot of moisture provides ideal conditions for the weed to take place. Seeds disperse within 40 days and germinate immediately, making green foxtail a very quickly growing and spreading weed.

Why is Green Foxtail a Problem?

While the weedy grass might look attractive and harmless to some, the potential to crowd out crops as well as pose threats to livestock is significant with green foxtail. It is known to compete with wheat, corn, and other agriculture and can potentially ruin a harvest if not treated carefully. The barbed hairs on the seed heads can become lodged in the faces and mouths of livestock during grazing and cause a host of health problems for them as well. On lawns, the weed is just unsightly.

Elimination of Green Foxtail

A combination of mechanical and chemicals is the best way of eradicating the pervasive weed, depending on the situation. Because of the constant germination period of the weed from the beginning of spring through the end of autumn, it is difficult to manage with a single approach. Professional lawn services and turf care experts can offer the best means of tackling green foxtail based on individual situations and conditions. Weed control with pre-emergent herbicides is a must to keep the weed off lawns.