HPIPM:Yellow foxtail

Taxonomy

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

Scientific Name

Setaria pumila

Scientific Name Synonyms

Setaria pumila ssp. pallidefusca

Setaria pallidefusca

Setaria pumila ssp. subtesselata

Setaria pumila ssp. pallidifusca

Common Name

yellow foxtail

Yellow foxtail (Setaria pumila)

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 241 by Marjolein Schat, Montana State University

Identification and Life Cycle

Yellow foxtail (Setaria pumila), also known as pigongrass, and yellow bristlegrass is an annual in the grass family (Poaceae). Seedling leaves are hairless except for long, wiry hairs on the upper side near the base. Mature plants are 1-3 feet tall with erect stems that branch at the base. Leaves on mature plants are smooth, 2-8 inches long and 0.5 inches wide. Auricles are lacking and leaves have a hair-like ligule. The floral structure (panicle) is cylindrical, with crowded spikelets that are subtended by 5 to 10 long yellowish bristles. Seeds are oval, green to yellow to dark brown, coarsely roughened, and approximately 0.12 inches long. Yellow foxtail has short fibrous roots. Yellow foxtail can be distinguished from other foxtails by the long white hairs on the upper leaf blades near the base, by the presence of five or more yellow or tawny bristles below each spikelet, and by the leaf sheaths which are smooth on the margins.

Habitats

Yellow foxtail is commonly found in crops, along the edges of fields, roadsides, and in waste areas. It grows in a wide variety of soil types and environmental conditions. However, yellow foxtail prefers full sunlight and does not persist in shaded sites.

Impacts

Yellow foxtail can be a serious problem in spring-seeded alfalfa, row crops, and small grain crops. It can cause reductions in yields and increased cleaning costs. If consumed in sufficient quantities, yellow foxtail can cause stomatitis in cattle and horses.

Biology and Ecology

Yellow foxtail reproduces exclusively by seed. Seedlings begin to emerge in may and yellow foxtail begins to tiller two weeks after emergence. Flowering and seed production occur from July through September. Yellow foxtail is self-pollinated and seeds begin to form even before the floral structure emerges from the surrounding leaf. The number of seeds produced per plant depends upon environmental conditions but has been reported to range from 540 to 8,460 seeds per plant. Seeds may remain viable in the soil for over 10 years. Seeds are dispersed by machinery, wind, and animals.

Management Approaches

Control depends on eliminating seed production until the soil seed bank is depleted. Herbicides are commonly used to control yellow foxtail.

Biological Control

There are no biological controls available.

Mechanical and Cultural Control

Close grazing by sheep can prevent a new crop of seeds from being shed. In natural areas, yellow foxtail can be mowed to eliminate seed production. However, since seeds may remain viable in the soil for over 10 years, repeated treatment may be necessary to deplete the soil 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.

For herbicide recommendations for specific grain rotations and weeds in Montana, please see the MSU Herbicide Chooser Tool.

Examples of herbicides that can be used to manage yellow 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
Sethoxydim	Inhibition of acetyl CoA carboxylase (ACCase)
*Poast Plus		1.5 - 2.25 pints	Apply before grass reaches 8 inches in height. Apply no later than 14 days before cutting. Poast Plus may be applied to seedling or established alfalfa and clover grown for hay, silage, green chop, direct grazing, or for seed.
Peas and Lentils
Quizalofop	Inhibition of acetyl CoA carboxylase (ACCase)
*Assure II		7 - 8 ounces	Apply to emerged weeds 2 to 6 inches tall. For best results apply when weedy grasses are in the 3-leaf to boot stage.
Grass Grown for Seed
Quinclorac	Growth regulator
*Paramount		5.3 ounces	Apply when annual weeds are small and actively growing.
Small Grains
Glyphosate	Inhibition of EPSP synthase
*Roundup Ultra Dry		9.5-19 ounces	Apply to actively growing weeds 6 to 20 inches tall in the spring or fall, before planting or emergence of the crop. Also may be applied prior to harvest or after harvest

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=yellow%20foxtail