The Enemy - Common Reed or Phragmites (Phragmites australis) is the devil weed of the grass family. This perennial plant not only has rhizomes but will also stolonate (sending roots down from the stems that lie along the ground). The plant can grow to a height of 10 to 12 feet, has roots that penetrate the hardpan that can reach a diameter of 1inch. The leaves can grow to a length of 2 feet and have leaf margins that become quite sharp and if one is trying to walk through it can cause serious cuts. The seed heads are feathery like and have been found if dried flower arrangements. This plant is devastating to many of the marshes, rivers, and canal banks around the pacific northwest.
The Strategy - It grows near water, thus invades river and lake banks. Once established it becomes so thick that the wildlife have no use for it and it prohibits native vegetation from striving. In marsh areas it can become so thick that it becomes a fire hazard, burning like a range fire out of control. It spread by roots thus invading many areas of healthy vegetation. If it has a good side to it, it is that it is good for stabilizing the banks to prevent erosion.
The Defense - This one of the toughest weeds to control. With such a diverse root system digging out the plant with a backhoe will only remove 30% of the plants and will grow back within a few years. Herbicides are somewhat effective. Aquatically approved Roundup with Ammonium sulfate added applied about three times a year will take out about 75% of the plant. First application should be in the spring, followed by one mid summer when the re-growth appears, and fall after the killing frost has appeared. Subsequent years of applications and a ‘keep at it’ attitude is the key to removing this plant.
PLEASE NOTE -The proper use and application of herbicides can be an effective way to control and eradicate noxious and invasive plants. Before using herbicides, always carefully follow the label and safety instructions on the label. While we recommend the use of herbicides as one of the effective tools for integrated pest management, the Idaho Weed Awareness Campaign assumes no liability for herbicide applications.
For more information, click on the link below to download the Idaho's Noxious Weeds Control Guidelines publication produced by the University of Idaho Extension.
U of I Idaho's Noxious Weeds Control Guidelines (183 KB PDF download)