- Pest Type: Weed
- Crops Affected: Cereals, Wheat, Cotton, Potatoes, Soybeans, Corn
- Scientific Name: Setaria glauca
- Pest Order: Poaceae
Yellow foxtail is a clump-forming, erect summer annual grass that grows to about 1 m in height; with characteristic "bottle-brush" or "foxtail" seedheads.
Reproduction is by seeds which germinate from late-spring through mid-summer. Seeds are 2-3 mm long, ridged, and yellow, with small dark markings.
The first blade is linear, about seven times longer than wide and opens somewhat parallel to the ground. Leaves are rolled in the bud; auricles are absent; and the ligule is a fringe of hairs about 0.02 inches long. The leaf blades of young seedlings are 1.7 to 3.2 inches long and 0.02 to 0.12 inches wide, smooth on the lower surfaces, with long wispy hairs on the basal portions of the upper surface. The margins are smooth or slightly rough, and the blade is keeled in the lower portion.
Leaf blades are about 30 cm long by 4-10 mm wide, keeled, and have long wispy hairs on the upper surface near the base. The sheath is smooth and compressed. The collar is green and smooth. The ligule is a fringe of hairs about 1 mm long.
The stem culm is branched from the flattened base, often growing along the ground; nodes are smooth.
Leaf blades are 11.8 inches long, with long hairs only on the upper surface near the base. The sheath is smooth, compressed, and often red at the base, with a prominent midvein. The collar is narrow, green or yellow, and remains smooth.
The root system is fibrous. This species does not root at the nodes, but tillers will produce roots at the base of the plant.
The mature seedhead is generally present from late summer through autumn. Yellow foxtail can be recognized by the yellowish, bristly inflorescence that persists through early winter. Other foxtails have persistent bristly inflorescences in the autumn, b
Yellow foxtail is a weed of most cultivated crops, as well as turf, landscapes, and nurseries. It generally grows on nutrient-rich soils. Seeds provide food and plants provide cover for birds.
Yellow foxtail is an important weed in most countries worldwide. It can be found throughout the United States and Canada.
Giant foxtail, green foxtail, and foxtail millet are similar, but can be differentiated by the ligules, leaf sheaths, and hairs on the leaves. Giant foxtail tends to be larger and its leaves have numerous short hairs on the upper surfaces and on the margins of the sheath. Green foxtail plants have rough leaf blades that lack hairs, and the sheaths have hairy margins. Fall panicum is also sometimes confused with yellow foxtail, but yellow foxtail can easily be identified by the wispy hairs at the base of the leaf blades.