Reed Canary Grass Control
(Displacement by a Diverse Native Species Mix)

Carl Kurtz
1562 Binford Ave.
St. Anthony, IA 50239

Reed canary grass (Phalaris arundinacea) is an invading cool-season perennial grass in mesic and wet areas throughout the northern half of the United States and is especially abundant in the Mississippi and Missouri River valleys. Abundant seed sources and its ability to spread by rhizomes make control difficult. This paper contains personal observations of control measures using diverse seed mixtures, frequent fire, and herbicide applications in spring and fall.

Introduction-Native and Eurasian varieties of reed canary grass (Phalaris arundinacea) are found along water drainage’s and in wetlands across the United States. Technically it is called a cyptogenic species, that is, its source origin is unknown. Historically, cultivation dates back to the mid-1700s in Northern Europe, while it has been planted in the US for forage and erosion control since the early 1900s. It is a tall cool-season (C3) grass which flowers in early June and drops abundant seed a week or so after flowering. It also spreads vegetatively by stout creeping rhizomes and can colonize up the sides of hills where the moisture gradient is favorable.

Many land managers feel that its coverage increases following high water cycles. This response to flooding seems to indicate it has the characteristics of a disturbance species. It appears to re-invade floodplains over time even if it is eliminated from a site.

Control Methods-The use of herbicides, frequent cultivation, fire, and mowing have all been used to remove or reduce its density. My observations indicate that solid stands can be successfully killed with fall applications of a contact herbicide. To obtain the best herbicide effect the grass should be mowed in early summer to prevent flowering and seed set and then mowed again in mid-October to make sure active growth continues with lots of new green leaves. An application of three or four quarts per acre of Round-up™ or Rodeo™ (if treating areas with standing water), in late October or early November will kill the rhizomes completely. While the action of the herbicide may not be apparent until the following spring, it appears that late fall applications are much more effective than a spring herbicide applications where many rhizomes seem to recover by mid- to late summer. I have also found Atrazine™ to be very effective, but its persistence in the environment and its effects on amphibians should preclude its use. Very close mowing or intensive grazing also appears to dramatically reduce stand densities.

My next step in control is the introduction of aggressive wet-tolerant native species to provide competition. It appears that the control of reed canary grass cannot be accomplished unless it is done by displacement with desirable native species.

Planting a diverse mixture of aggressive mesic and wet species is the first step. Table One includes a list of species that appear to be site-adapted in the upper mid-west. In concert they provide the competition necessary to stop the spread of the grass. In the case of saw-tooth sunflowers I have seen evidence of invasion into solid stands of reed canary grass.

Once a diverse group of native species has been established, one can aid their development by spraying the new growth or persistent re-growth of reed canary grass in the spring with a soybean herbicide such as Poast™ or Select™. These soybean herbicides are used to control cool-season grasses such as foxtails. They stunt the growth of cool-season perennial grasses such as reed canary and smooth brome, but have no effect on forbs. If the herbicide is applied in spring (late April in the upper mid-west) when the new leaves of the canary grass are 6 to 10 inches tall, it will set the plant’s leaves back to the ground for 6 to 8 weeks and also prevent its flowering and seed production for that season. In the meantime, the growth of the native plants will benefit from the reduced competition. When reed canary grass starts growing again in mid-summer the natives will have canopied over its top.

Results-My efforts at reed canary grass displacement were applied to a wet drainage of about two acres and have continued over a period of five years. I have continued to add diverse seed, inserted plugs of prairie cord grass, and occasionally wicked the growing stems and leaves of reed canary grass with a 30 percent Round-up™ solution. It appears from photo documentation and casual surveys that reed canary grass coverage in 2002 was reduced from its original coverage in 1997 by more than 95 percent. Because of the wet nature of this area it has not been burned or treated with herbicides some years, yet it appears that the diverse assemblage of native plants is winning the battle for space. My goal is not the complete eradication of reed canary grass, but a diverse dynamic wetland plant community. In conclusion it appears that reed canary grass can be controlled effectively by planting of a diverse mix of wetland species and aiding the establishment process with the use of properly timed herbicide applications.

Table 1. Twenty-one important species for reconstructing a wetland prairie in the Upper Midwest.

Scientific Name Common Name
Andropogon gerardii Big Bluestem
Asclepias incarnata Swamp Milkweed
Caltha palustris Marsh Marigold
Circuta maculata Water Hemlock
Eupatorium maculatum Joe-pye Weed
Eupatorium perfoliatum Common Boneset
Gentiana andrewsii Bottle Gentain
Helianthus grosseserratus Saw-tooth Sunflower
Iris shrevei Blueflag Iris
Juncus sp. Spike Rushes
Lythrum allatum Wing-angled Loosestrife
Lobelia siphilitica Great Blue Lobelia
Lycopus americanus Cut-Leaved Water-Horehound
Panicum virgatum Switchgrass
Pycnanthemum virginianum Mountain Mint
Scirpus fluviatilis River Bulrush
Silphium laciniatum Compass Plant
Solidago rigida Rigid Goldenrod
Spartina pectinata Prairie Cordgrass
Thalictrum dioicum Meadow Rue
Veronica fasciculata Common Ironweed

Selected References

Carlton, J.T. 1996. Biological invasions and crypotogenic species. Ecology 77:1653-1654.

Hiebert, R. D. and James Stubbendieck, 1993. Handbook for Ranking Exotic Plants for Management and Control. U. S. Department of the Interior, National Park Service, Natural Resources Publication Office, Denver, Colorado.

Hoffman, R. and Kelly Kearns. 1997. Wisconsin Manual of Control Recommendations for Ecologically Invasive Plants. Wisconsin Department of Natural Resources. Madison, Wisconsin.

Kurtz, C. 2001. A Practical Guide to Prairie Reconstruction. University of Iowa Press, Iowa City, Iowa.

Pasture and Range Plants. 1963. Phillips Petroleum Company, Bartlesville, Oklahoma.

Pohl, R. W. 1966. The Grasses of Iowa. Iowa State Journal of Science 40(4):341-566. Ames, Iowa.

Pohl, R. W. and Lynn Clark. 1996. Agnes Chase’s First Book of Grasses. Smithsonian Institution Press. Washington and London.

Rosburg, T.R. December 2001, Iowa’s Non-native Graminoids. Proceedings of the Iowa Academy of Science 108(4):142-149.