Quackgrass

Elytrigia repens (L.) = Elymus repens (L.) = Agropyron repens (L.)¹

Family: Poaceae (Grass family)¹

Common Names - quitch grass, couch grass, wheat grass, shelly grass, knot grass, scotch grass, quick grass, twitch grass, witchgrass, devil’s grass, bluejoint, pondgrass, Colorado bluegrass, false wheat, dog grass, seargrass, quickens, wickens, stroil¹

History

Quackgrass is native to Europe. It was introduced to North America with some of the first European colonists in the 17th century likely as a contaminant in hay.² The species spread westward along with settlements, likely through the transportation of quackgrass contaminated hay and straw and the sowing of contaminated bromegrass seed. Quackgrass first attracted serious attention as a weed in the United States about 1837.³

Because quackgrass does not tolerate long, hot summers it is not present in desert environments and is more prevalent in northern states.⁴

Noxious Weed Status for Surrounding States:

Idaho - No    Washington - No    Oregon - No    Nevada - No    Utah -Yes Wyoming - Yes   Montana - No

Quick Identification

General - Leaves are an ashy, blue-green color and can sometimes have a longitudinal twist.⁵ A useful identification characteristic of quackgrass is the constriction or crimp in the leaf blade approximately 1 to 2 inches from the tip.⁴ Mature leaves of quackgrass are often wider than most lawn grasses.⁵ In a farm field, many of the vegetative characteristics are similar to those of wheat, quackgrass leaves may be a slightly darker shade of green and slightly wider than those of wheat. Pulling up a quackgrass shoot will reveal the rhizome system, which is not present in wheat.³ The two main identifying features are clasping auricles and rhizomes.

Common Look Alikes - Other rhizomatous wheatgrasses such as intermediate wheatgrass (Thinopyrum intermedium), thickspike wheatgrass (Elymus lanceolatus ssp. lanceolatus) and western wheatgrass (Pascopyrum smithii).⁶

Further Physical Description

Flower - The inflorescence is a 2–8 inch-long, flattened spike with two alternating rows of numerous 0.4–0.6 inch-long spikelets. The spikelets may have 0.07–0.4 inch-long awns at the tips. The inflorescence turns from greenish blue to straw colored as it matures. Each spikelet produces four to six tan, narrow, oblong, 0.04–0.2 inch-long seeds. As with all grasses, the apparent seed includes a tight, thin outer layer of fruit tissue.¹

Leaf - The leaves are flat, drooping and range from 4 to 12 inches long. The underside of the leaves has a waxy coating, and the upper leaf surface has either a hairy or waxy coating. A useful identification characteristic of quackgrass is the constriction or crimp in the leaf blade approximately 1 to 2 inches from the tip. The collar has narrow, clasping auricles.⁴

Stem - The stems often lay horizontal from the base of the plant and then bend upwards.⁴

Fruit/Seed - It typically produces 25–40 seeds per stem. However, seedlings are rarely observed, probably because many seeds are sterile. The species requires cross-pollination, and many populations apparently consist of just one to a few clones, making effective pollination difficult. Seed production serves mainly to disperse the species between sites rather than to maintain the population at a particular site.¹ Seed typically falls from the plant in late summer and can remain viable for 1 to 6 years,4 but in normal field conditions few will survive longer than three years.¹

Roots - Quackgrass produces an extensive rhizome system that has been reported to grow as fast as an inch per day.4 The rhizomes can spread up to 24 inches horizontally and extend to 8 inches below the soil surface. The root system is composed of spreading rhizomes with pointed tips and fibrous roots at the nodes.¹ The rhizome tips are sharp, enabling them to penetrate hard soil, roots, and tubers (such as potatoes).⁴ In heavily infested fields, rhizomes can weigh as much as 7–9 tons per acre.¹

Quackgrass reproduces primarily by rhizomes. The rhizomes can remain viable through long periods of desiccation, and fragmented rhizomes can give rise to new plants.⁴

Dispersal and Propogation - Most reproduction in a given field or garden is vegetative, with shoots arising from the tips of each rhizome branch. Rhizomes can spread up to 10 feet per year from the parent plant. A single rhizome node planted in late fall in Pennsylvania produced 14 rhizomes with a total length of 458 feet by the following fall. If tillage or deep hoeing breaks rhizomes, most segments will produce an aboveground shoot. These shoots become independent of the rhizome fragment at the five-leaf stage and begin producing new rhizomes at the three- to four-leaf stage.¹

Production of new rhizomes is favored by a moderate temperature of 70°F with long day length typical of May or June conditions. In contrast, production of rhizomes that grow upward to establish new shoots is favored by either a low temperature of 50°F, such as occurs in April or November, or by a high temperature of 90°F, as occurs during mid-summer.¹

Dealing with Quackgrass

Prevention

Seeds are dispersed in hay used for mulch, in manure, and as a contaminant of grain seed (e.g., used for cover crops). Rhizomes are also sometimes dispersed in the soil surrounding the roots of nursery stock. The rhizomes are commonly dispersed on tillage machinery. Recommend to buy clean hay, nursery stock, and clean machinery of rhizomes regularly.¹

Susceptibility 

Drought - Quackgrass prefers moist sites but is fairly drought and salt tolerant.⁴

Shade - Does not tolerate continuous shade.⁴

Timing - Rhizome reserves are at a minimum when the shoot has developed three leaves, so try to target tillage and cultivation at that growth stage, but disturbance is useful whenever the shoot is showing.¹

Mechanical 

The extensive root and rhizome system of quackgrass makes it extremely difficult to control by mechanical or cultural means alone. Its abundant food reserves and ability to regenerate from rhizome fragments make mechanical control problematic.⁴

Hand-pulling - usually not a practical control measure, especially for larger infestations.⁴

Mowing - Repeated post-harvest mowing reduced rhizome production and increased grain yield in the subsequent year.¹

Burning - Not usually very effective for quackgrass suppression. Late spring fires generally reduce cover, plant biomass, and flowering, while early spring fire can have the opposite effect. Quackgrass normally recovers rapidly after a fire due to the amount of stored root reserves.⁴

Tilling - The effectiveness of tillage is variable and depends on the severity and frequency of the infestation. Tillage can actually stimulate new shoots to form by severing the terminal bud from the rest of the rhizome. A single disking or cultivation alone is usually not very effective and may spread the rhizomes. However, disking or cultivation after plowing can be beneficial. It can help chop roots and rhizomes and bring them to the surface where they can desiccate.⁴

The first tillage of the year should be aimed at cutting the rhizomes into the smallest pieces possible. Thus, beginning with rotary tillage or disking is more effective than moldboard or chisel plowing. Following the initial tillage with moldboard plowing, however, is often useful for placing the small rhizome pieces deep in the soil. They will then have to use up substantial reserves to reach the surface. Buds on quackgrass rhizomes will sprout at any time during the growing season, so many opportunities to deplete reserves occur before and after a summer crop. For example, before soybeans or a summer vegetable crop, till the soil when quackgrass begins to grow and then delay a few weeks before preparing a seedbed. Unlike a re-worked seedbed for depleting a surface seed bank, however, tillage for seedbed preparation should work the top 6 inches to disturb as many rhizome fragments as possible. If necessary, this procedure can be repeated in the fall after harvest, followed by winter grain as a cash or cover crop.¹

The fastest way to rapidly control a severe quackgrass infestation is to thoroughly dry out the rhizomes. The traditional English method is to plow the soil when it is wet so that it becomes cloddy. Then stir the clods repeatedly during dry weather so that the whole plow layer becomes thoroughly dry.¹

A less effective method that does not require such a long fallow begins by tilling the soil with a chisel plow or field cultivator at the beginning of a dry period. The aim of the tillage is to loosen the soil around the rhizomes while leaving the rhizome pieces as long as possible. Then use a spring tooth harrow to work the rhizomes to the soil surface to dry. Use the harrow every few days to speed drying of the soil and bring more rhizomes to the surface so that most dry thoroughly before the next rain. If the infestation is particularly dense and the field is small, you can remove a substantial percentage of the rhizomes by bringing them to the surface as explained above and then raking them onto the field margins. A window of opportunity for this approach is often available in late summer after harvest of a cereal grain or short season vegetable crop. Beginning tillage immediately after harvest and preventing fall quackgrass growth is more important than repeated cultivations later in fall.¹

When row crops are in the ground, continue to cultivate as long as you can get between the rows safely. The more times the quackgrass shoots are cut off at about the three-leaf stage, the more you will weaken the rhizomes.¹

Obviously, the intensive tillage discussed above will tend to deplete soil organic matter and pose a potential erosion risk. Consequently, they should be used only when quackgrass has become a severe problem or appears likely to become so. Moreover, when using these practices, you should compensate for the reduced soil organic matter by incorporating cover crops into the crop rotation. Also, proper equipment can reduce the impact of quackgrass control practices on soil health. For example, a field cultivator equipped with broad, shallow sweeps can be run shallowly after crop harvest to cut off quackgrass shoots while maintaining crop residue on the soil surface. When cultivating row crops, shallow low-pitch blades will sever the quackgrass shoots with less oxidation of soil organic matter and disturbance of crop roots than more conventional sweeps and shovels.¹

Cultural 

Cover Crops - Under-sown cover crops also have the potential to control quackgrass if they can attain growth of at least 900 pounds per acre. Interseeding red fescue with a winter wheat cash crop at planting will suppress quackgrass, whereas red clover can actually benefit rhizome production. A dense, vigorous stand of winter grain like wheat can competitively suppress quackgrass.¹

Grazing - Cattle, sheep and horses find quackgrass desirable forage. Pigs will grub out the rhizomes and eat them.¹ Normal grazing often has minimal effect on quackgrass. It is difficult to significantly deplete the carbohydrate reserves stored in the extensive rhizome system.⁴

Biological 

There are no biological control agents available for the management of quackgrass.⁴

Sources:

1. Mohler, Charles L. et al. “Quackgrass”, Sustainable Agriculture Research and Education  Outreach, 2021 https://www.sare.org/publications/manage-weeds-on-your-farm/quackgrass/ Accessed June 2026

2. “Quackgrass Elymus repens (L.) Gould”, Teton County Weed & Pest District https://www.tcweed.org/invasive-plants/quackgrass Accessed June 2026

3. Sanders, Suzanne M. and Thill, Donald C. "Quackgrass control with Maverick & other herbicides in dryland wheat production systems in northern Idaho", Agricultural Experiment & UI Extension Publications, October 1999, University of Idaho Library Digital Collections, https://www.lib.uidaho.edu/digital/uiext/items/uiext31247.html Accessed June 2026

4. DiTomaso, J.M. and G.B. Kyser et al. “Quackgrass Weed Report”, Weed Control in Natural Areas in the Western United States, 2013, University California Davis https://ucdavis.app.box.com/s/t266vkfh1ym7bb7j57k5ufkrv9vrby3v/file/2053586260091 Accessed June 2026

5. Patton, Aaron and Law, Quincy. “Quackgrass”, 19 June 2015, Turfgrass Science at Purdue University https://turf.purdue.edu/quackgrass/ Accessed June 2026

6. Trujillo, Justin J. and Strand, Eva K. “A Field Guide to Grasses and Grass-Like Plants of Idaho”, University of Idaho Extension Publication, 31 August 2018

7. “Elytrigia repens”, Solve Pest Problems, 3 April 2026, Oregon State University https://solvepestproblems.oregonstate.edu/weeds/quackgrass