Although common reed (Phragmites australis) is a native European grass, it has made its way into the United States and is considered an exotic "invasive species." Invasive species do not have any natural predators on this continent to control their population. Therefore, they have the ability to out-compete native vegetation and form dense stands.

What Does Common Reed Look Like?

Common reed has erect stems that grow up to 15 feet high and end in dense floral heads. These floral heads are purplish when young, and white or light brown and feathery when mature. Common reed’s sharp, long, pointed green leaves grow up to 2 feet long and 2 inches wide. It flowers from late July through October and can be found throughout southern Canada and the United States.

Why Does Common Reed Grow So Quickly?

Stands of common reed disperse seeds, or pieces of underground stems, called rhizomes. Once established, stands grow predominately by sending up new shoots each spring from existing rhizomes, or from runners, called stolons. If an aerial shoot is knocked over, it can act like a rhizome, taking root and producing new shoots. This grass can return year after year, and some stands are believed to be 1,000 years old!

Where Does Common Reed Grow?

Common reed grows in sunny, wetland habitats. It is found in fresh and alkaline marshes, pond margins, swamps and ditches. Not only does it thrive in freshwater habitats but it can tolerate brackish waters as well. It is prevalent in wet areas that have disturbed or polluted soils. Human activities, such as road and housing development, have made the invasion of common reed quite successful in adjacent wetland areas.

Why Should I Care About Common Reed?

• Common reed spreads quickly and can tolerate a range of environmental conditions.

• The accumulation of dead leaves, stems, and rhizomes can prohibit the growth of native, more desirable wetland plant species, such as cattail, rushes, and reeds.

• Common reed does not have any natural predators to control its population. Therefore, it has the ability to compete with native vegetation and form dense stands.

• Common reed germinates quickly, thereby reducing habitat size and displacing native wildlife.

• Common reed has little food value to native wildlife. Recent studies have shown that marsh fish do not reproduce in stands of common reed.

• Because of its hollow structure and abundant plant material, common reed is also an extreme fire risk. The plants dry easily, burn with extreme intensity, and can accelerate fire travel. History has shown that a Phragmites fire is a fast-moving hot fire that can engulf adjacent structures.

What Can Be Done To Prevent The Spread Of Common Reed?

The best way to prevent the spread of common reed is to Minimize land disturbances, implement erosion control measures, and monitor fluctuating water and nutrient levels adjacent to wetlands. However, once common reed has established itself in a wetland, it is extremely difficult to eradicate. Maintaining healthy wetland ecosystems and employing best management practices will help curb this invasive, exotic species from destroying the remaining wetlands in New Hampshire, and elsewhere in the U.S.

Another eradication option is the EPA-registered herbicide, glyphosate, (trade name Rodeo). The potential water quality impacts of applying glyphosphate are minimal. Tests reveal that it is virtually non-toxic to all aquatic animals. It biodegrades quickly and completely into natural products, including carbon dioxide, nitrogen, phosphate, and water. Studies show it can be used without posing unreasonable risks to people or the environment. It is most effective when applied in the early fall when nutrients are displaced from the leaves and stems for storage in rhizomes. A permit from the Department of Agriculture is required to purchase and/or use Rodeo in New Hampshire wetlands.

In the winter, dead stands can be cleared by cutting/mulching to open the area for desired species. The process usually needs to be repeated in the second year to reduce the number of remaining plants, and repeated every three to five years after that. In any case, there is no easy solution to control this invasive species.

For more information contact the New Hampshire Coastal Program at (603) 431-9366 or visit www.des.nh.gov/coastal.