Setaria viridis (L.) P. Beauv

Giant Green Foxtail, Green Bristlegrass, Green Foxtail, Green Millet

Category
Grass

Description

A summer annual grass, green foxtail (Setaria viridis) has a fibrous root system and reproduces by seed. It grows 1 to 4 feet (15 to 115 em) tall and is erect rather than sprawling.

Stem

Stems are smooth and usually hollow in the center. The leaf sheath is smooth except for the margins, which are lined with short upward-pointing hairs that are especially noticeable near the collar. The ligule is a fringe of hairs about 1/16 inch (1 to 2 mm) long. Auricles are absent.

Leaves

Leaf blades are flat, up to 10 inches (25 cm) long, and ¼ to ¾ inch (6 to 18 mm) wide. They have sharply pointed tips and a rounded base. The upper surface of the mature leaf blades varies from smooth to sparsely hairy; the lower surface is always smooth. Leaf blade margins may be smooth or slightly rough.

Flowers and Fruit

The mature seedhead is a fuzzy tapered cylinder, 1 to 5 inches (2.5 to 12 cm) long, and ½ to 1 inch (1 to 2.5 cm) wide, including awns. Awns are usually green, but occasionally purple, and all are covered with tiny barbs. The barbs point upward, so the panicle feels soft and fuzzy when stroked toward the tip. The panicle is usually erect but may nod slightly.

Images

Photo: Wendy VanDyk Evans, Bugwood.org
More images of Setaria viridis

Life History

Habitat

Green foxtail grows best in sandy to loamy soils that have good fertility and plenty of moisture. It grows in cultivated fields, gardens, and other disturbed soil, in pastures, lawns, and waste places, and along roadsides and embankments. The weed is an alternate host for nematodes, Meloidogyne species, and for the virus that produces black-streaked dwarf diseases of rice.

Origin and Distribution

The most common Setaria species in the northeastern United States, green foxtail was originally introduced from Europe, probably as a contaminant in crop seed and in the ballast of ships. It is a problem in temperate countries throughout the world. In the tropical belt, it grows only at high elevations where temperatures are cool.

Green foxtail grows well and competes heavily in cereals and vegetables, and in legume crops such as peas, beans, and lentils. In the United States it is a principal weed of com, soybeans, sorghum, sugar beets, cotton, flax, and cereals. It also infests pastures, orchards, vineyards, many vegetables, and irrigated crops. While natural stands of foxtail are sometimes used for pasture, the weed is generally not encouraged because it is so competitive that it can crowd out desirable species.

The genus name Setaria derives from the Latin seta, meaning "bristle." The species name viridis means "green." The common name clearly describes the weed's long, fuzzy panicle. In the United States, green foxtail is also known as bottle grass, green bottle grass, green bristle grass, pigeon grass, and wild millet.

Green foxtail can been found in the following states/territories: USA (AK, AL, AR, AZ, CA, CO, CT, DC, DE, FL, GA, IA, ID, IL, IN, KS, KY, LA, MA, MD, ME, MI, MN, MO, MS, MT, NC, ND, NE, NH, NJ, NM, NV, NY, OH, OK, OR, PA, RI, SC, SD, TN, TX, UT, VA, VT, WA, WI, WV, WY), CAN (AB, BC, MB, NB, NF, NS, NT, ON, PE, QC, SK, YT)

Synonyms

Setaria glauca (L.) Beauv.

h2. Management Recommendations

Since seeds can germinate over the entire summer, full-season control of this weed may be difficult. A combination of cultural and chemical controls is advised. Most preemergence herbicides are effective in controlling foxtail if applied at the recommended time and rate. However, herbicides applied very early in the season often lose their effectiveness by the time foxtail germination is at its peak. This can cause foxtail problems in fields planted early.

Mechanical Controls

Mowing before foxtail seeds mature is a cost-effective way to prevent its spread in solid stand forages.

Herbicidal Controls

Apply herbicide and mowing treatments before flowering/seed production

Apply a glyphosate herbicide as a 0.5 to 2-percent solution in water (2 to 8 ounces per 3-gallon mix) with a surfactant in early summer; or apply Fusilade DX or Plateau in summer for situations that require more selective control and less impact on associated plants (hand weeding a month prior to these treatments will increase control and revegetation diversity).

Repeat treatments for several years to control abundant germinating seeds. Mowing or pulling just before seed set will also prevent seed buildup in the soil seed bank. An early summer seed crop is hidden inside the leaf sheaves.

Bibliography

Lanini, T.W. and Wertz, B.A. Penn State Extension. College of Agricultural Sciences. Green Foxtail.

Miller, J.H. Manning, S.T. and Enloe, S.F. 2010. A Management Guide for Invasive Plants in Southern Forests. Southern Research Station, Asheville, NC. 90 pp.

USDA, NRCS. 2010. The PLANTS Database, PLANTS profile for Setaria viridis (L.) P. Beauv "green bristlegrass":http://plants.usda.gov/core/profile?symbol=SEVI4