HPIPM:Quackgrass

Taxonomy

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

Scientific Name

Elymus repens

Scientific Name Synonyms

Triticum vaillantianum

Triticum repens

Elytrigia vaillantiana

Elytrigia repens

Agropyron repens

Agropyron repens var. subulatum

Common Name

quackgrass

Quackgrass (Elytrigia repens)

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 Colorado Weed Management profile for quackgrass by Marjolein Schat, Montana State University

Identification and Life Cycle

Quackgrass (Elytrigia repens)has several scientific synonyms including Elymus repens, and Agropyron repens. Quackgrass, also called couchgrass, is a perennial in the grass family (Poaceae). Seedling leaves and sheaths are hairless to sparsely hairy. Mature plants have erect stems that reach a height of 1 to 3 feet. Leaves on mature plants are flat, pointed, 0.25 to 0.5 inches wide. Leaves have clasping auricles and a short membranous ligule. Quackgrass flowers form on a slender spike that resembles wheat heads. Spikelets are arranged in two long rows. Florets are awnless or with short strait awns.

Habitats

Quackgrass is well adapted to moist soils in cool temperate climates and is only moderately shade tolerant. It invades mixed-grass prairies, roadsides, ditches, crop fields, gardens, yards, and disturbed moist areas.

Impacts

Quackgrass reduces productivity in crops, rangeland, and pastures. Quackgrass is a rapid invader and quickly stabilizes moist eroding soils.

Biology and Ecology

Quackgrass propagates primarily by rhizomes, but also reproduces by seed. Primary rhizome growth begins in early spring and then again in September and October with the onset of fall rains and cooler temperatures. Quackgrass flowers from June through August. Cross-pollination is necessary for seed production. Seeds germinate in fall or spring and plants are capable of producing seeds more than once per season. Seeds may remain viable for up to 10 years. Although quackgrass is considered an undesirable weed species it has been crossed with other wheatgrasses to create hybrids for grazing.

Management Approaches

Quackgrass is an early seral species in disturbed areas. This species initially forms a dense clump through extensive tillering. The following season plants may expand and form patchy to pure stands. Management objectives for quackgrass control should combine prevention and controlling spread of the plants in natural communities.

Biological Control

No biological control agents are currently available for control of quackgrass.

Mechanical and Cultural Control

Repeated tilling can effectively control quackgrass if conducted from the beginning of August until the ground freezes. Although, tillage will cause a disturbance and may harm desirable, native species. Repeated mowing to a height of 5 cm or less may reduce plant vigor and seed production. Mowing is most effective when the plant is actively growing in the spring and fall and should be suspended when desirable plants begin to grow. The plant is palatable to livestock and provides a good spring and summer forage. Quackgrass starts to grow earlier in the spring than other grass species; therefore, grazing should be concentrated in the early spring to reduce plant vigor and quackgrass populations.

Chemical Control

A number of herbicides can successfully control quackgrass. 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 quackgrass

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
Fluazifop	Inhibition of acetyl CoA carboxylase (ACCase)
*Fusilade DX		12 ounces then 8 ounces	Two applications necessary. Make first application when quackgrass is 6 to 10 inches tall and the second application 2 -3 weeks later before quackgrass exceeds 10 inches tall.
Canola
Quizalofop	Inhibition of acetyl CoA carboxylase (ACCase)
*Assure II		10 - 12 ounces	Quackgrass control may require two applications. Apply when quackgrss is 6 to 10 inches tall.
Roundup Ready Corn
Glyphosate	Inhibition of EPSP synthase
*Roundup Ultra Dry		1.2 - 3.5 pounds	Roundup Ready corn only. Apply before emerged weeds become competitive with corn (when grass is less than 6 inches tall), but before corn reaches v-8 stage or 300 inches tall
Peas and Lentils
Sethoxydim	Inhibition of acetyl CoA carboxylase (ACCase)
*Poast		1.5 - 2.5 pints	Apply before quackgrass reaches 8 inches in height.
Grass Grown for Seed
Glyphosate	Inhibition of EPSP synthase
*Roundup Original		1 - 3 quarts	Make applications before, during, or after planting or for renovation. For maximum control of existing vegetation, delay planting to determine if any regrowth from escaped underground plant parts occurs. Apply when quackgrass is 6 to 8 inches tall.
Small Grains
Glyphosate	Inhibition of EPSP synthase
*Roundup Original		1 - 3 quarts	Apply when quackgrass is 6 to 8 inches in height. Roundup can be applied pre or post emergence or post 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=quackgrass&Start=1&results=47

http://plants.usda.gov/java/profile?symbol=ELRE4

http://www.agdepartment.com/noxiousweeds/pdf/Quackgrass.pdf