HPIPM:Green foxtail

Taxonomy

Domain	Eukarya
Kingdom	Plantae
Phylum	Magnoliophyta
Class	Magnoliopsida
Superorder	Lilianae
Order	Poales
Family	Poaceae
Genus	Setaria

Scientific Name

Setaria viridis

Scientific Name Synonyms

Setaria italica ssp. viridis

Common Name

green foxtail

Green foxtail (Setaria viridis)

Author: The Colorado Department of Natural Resources, Colorado State Parks, and Colorado Natural Areas Program - in partnership with the Division of Plant Industries in the Colorado Department of Agriculture.

Adapted from Appendix 4: Profiles of Colorado State-Listed Noxious Weeds, page 243 by Marjolein Schat, Montana State University

Identification and Life Cycle

Green foxtail (Setaria viridis), also called pigongrass, green bristlegrass, and wild millet is an annual in the grass family (Poaceae). Seedlings have hairless leaf blades and sheaths that are hairless except for short hairs along the margins. Mature plants are 1-3 feet tall, with erect stems that branch at the base. Leaves are flattened and usually less than 6 inches long. The leaf sheath is roughened and hairless. Leaves lack auricles and have a hair-like ligule. Flowers are cylindrical with crowded spiklets that are subtended by 6 to 10 long yellowish bristles. Seeds are oval and greenish to dark brown.

Habitats

Green foxtail is commonly found in irrigated crops, lawns, gardens, along roadsides, streams, and waste places. It prefers moist medium to coarse textured soils.

Impacts

Green foxtail is a nuisance in cultivated fields and irrigated valleys and can be a serious problem in spring-seeded alfalfa, small grain, and row crop where it can lead to yield reduction and increased cleaning costs.

Biology and Ecology

Green foxtail reproduces by seed. Green foxtail is a summer annual that overwinters as a seed. It emerges in April or May following periods of high rainfall. Flowering occurs from July to September and seeds can mature within two weeks of flowering. The seeds of green foxtail readily fall from the flower structures when mature. Green foxtail typically produces between 5,000 and 12,000 seeds per plant. However, the number of seeds per plant is highly dependent upon the size of the plant. Seeds are distributed by human activity, animals, birds, and water and can remain viable in the soil for up to 6 years.

Management Approaches

Control of greed foxtail depends on eliminating seed production until the soil seed bank is depleted.

Biological Control

There are no biocontrol agents available for green foxtail.

Mechanical and Cultural Control

In natural areas, green foxtail could be mowed or cut to prevent seed production, but repeated treatments are necessary to deplete the seed bank.

Chemical Control

There are multiple reports of herbicide resistance in green foxtail in France, Spain, Yugoslavia, Canada, and the United States. In the United States resistance has been reported for Dinitroanilines in North Dakota, and ALS inhibitors in Wisconsin. For a complete list of reports of resistance please see http://www.weedscience.org/Summary/USpeciesCountry.asp?lstWeedID=153&FmCommonName=Go.

Examples of herbicides that can be used to manage green foxtail

Consult herbicide labels for additional rate, application, and safety information. Additional herbicide information can be found at http://www.greenbook.net.

Herbicide Active Ingredient trade name	Mode of Action	Product per Acre	Application Time or Growth Stage
Alfalfa
Quizalofop	Inhibition of acetyl CoA carboxylase (ACCase)
*Assure II		7 - 8 ounces	Apply when grasses are between 2 and 4 inches tall.
Canola
Sethoxydim	Inhibition of acetyl CoA carboxylase (ACCase)
*Poast		1 - 1.5 ounces	Apply before grasses reach 8 inches tall. Minimum time between application and harvest is 60 days.
Corn and Sorghum
Dicamba; diflufenzopyr; nicosulfuron	Action like indole acetic acid (synthetic auxins), Inhibition of acetolactate synthase ALS (acetohydroxyacid synthase AHAS)
*Celebrity Plus		4.67 ounces	Apply to actively growing green foxtail 2-4 inches tall when corn is 4 to 24 inches tall.
Peas and Lentils
Quizalofop	Inhibition of acetyl CoA carboxylase (ACCase)
*Assure II		7 - 8 ounces	Apply when grasses are between 2 and 4 inches tall.
Grass Grown for Seed and Fallow
Quinclorac	Growth regulator
*Paramount		5.3 ounces	Apply when annual weeds are small and actively growing.

The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality.

References

For more information and images please visit IPM Bugwood. http://www.ipmimages.org/search/action.cfm?q=Green%20Foxtail&Start=1&results=24