Common Reed
Phragmites australis

THREAT: Common reed, or phragmites, is found on every continent except Antarctica. Although common reed is native to North America, a non-native genotype from Europe has been introduced and has become invasive. Common reed grows along the edges of still or slow moving, freshwater, brackish or alkaline water bodies (ponds, sloughs, slow moving streams, roadside ditches). It can form dense stands and continuous fringing belts along the water. The invasive form can outcompete native wetland plants, eliminating wildlife habitat and sometimes physically altering wetlands by trapping sediment. Common reed reproduces both by large quantities of wind and water dispersed seed and by rhizomes. Rhizome fragments can be moved by water or in contaminated soil or equipment. Once a new stand is established, it spreads primarily through vegetative means. In eastern Washington, common reed is taking over areas where purple loosestrife, another invasive wetland plant, has been killed by biological control methods.

DESCRIPTION: Common reed is a large perennial grass that grows up to 16 feet tall. It has a rhizomatous root system, allowing it to spread vegetatively. The hollow stems can be up to 1 inch in diameter, and leaves are flat and stiff, growing up to 2 feet long. The thin ligules have a fringe of hair-like structures along the top. Flowers are borne in large (1-2’) feathery panicles, which are purplish when in bloom, and changing to grayish or straw-colored as the seeds mature. Common reed flowers between July and September, and seeds are shed from November to January. Young plants in newly colonized sites may remain small for a couple of years before assuming the usual tall growth form. After seed set, the above ground portions of the plant die, and new shots emerge from the root system in the spring.

MANAGEMENT OPTIONS: Common reed can be controlled using cultural, mechanical and chemical means. It is critical to monitor any controlled site in subsequent years to prevent reestablishment of the plant. Common reed can be controlled using a carefully timed program of cutting for multiple years. Cutting is most effective when done in the middle of the summer (end of July). Cutting at the wrong time will encourage growth and increase stand density. Cutting can also be used in combination with herbicide application. All cut material must be removed from wetland areas to prevent resprouting. Draining, dredging, flooding, grazing and mowing may be used with some success but need to be carefully timed. A combination of mowing and discing has also been used. Hand pulling of small infestations can be effective in sandy soils. Laying of black or clear plastic has also been used with some success. Contact the weed board for site-specific chemical recommendations.