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Late Summer is the Ideal Time to Control Stands of Invasive Phragmites

Invasive phragmites (phragmites australis) is a non-native threat in Michigan and surrounding states that requires prompt identification and control in order to maintain healthy native communities around ponds, along lakeshores, and in wetland areas.

Late Summer is an ideal time to control pioneer stands of invasive phragmites. By this time of year, the plants have matured and set seed heads, making it relatively easy to identify. The stage of maturity also makes herbicide treatments more effective because the plant is actively moving the energy stored in the plant back into the root system, and will transport the herbicide along with it.

Invasive Phragmites Control

If undetected, invasive phragmites can become established and in a matter of a couple of years a small pioneer colony can become a menace to native plants and animals and be very difficult to control (a “pioneer colony” typically occurs as seeds spread and may be only a small number of plants). The sooner you detect the problem and take action, the less likely the plant is to become established.

The first step for control of invasive phragmites (sometimes called “exotic phragmites”) populations is to be able to identify it. Invasive phragmites is a very tall reed-like grass that can grow over 15 feet in height, however it is often much shorter and less dense in pioneer stands. It grows primarily in wetland areas such as marshes, fens, swamps and along shorelines and pond edges, however because of its deep root system it is also able to invade upland areas with relatively high water tables.  Once established, invasive phragmites grows very rapidly and forms a dense monoculture (when there is only one type of plant in a given area) that inhibits the growth of native plants.

There is also a strain of native phragmites (phragmites americanus) that is smaller and does not pose the same threat as invasive phragmites. Typically, native phragmites grows sparsely and grows among other wetland species and usually is less than 6.5 feet tall. Native phragmites stems also tend to break down each winter, so there usually aren’t dense stands of dead stalks that persist through the year. Native plants are reddish-purple at the base, the leaves tend to be yellow-green with sheaths that readily fall off the stems in the fall. Invasive phragmites leaves are bluish-green and the leaves are more difficult to pull off and the sheaths stay attached to the stalk year-round, additionally the heavy dead stalks tend to persist for several years, creating dense stands of dead stalks amid the growing plants. When in doubt, contact an expert.

Why Is Invasive Phragmites Such a Concern?

Invasive phragmites has become a threat not only in Michigan, but in many other states as well. Invasive phragmites grows extremely aggressively, and when it is introduced into an area, it dominates and takes over. It is incredibly adaptable and reproduces both through rhizomes (horizontal roots that send up new plant shoots) and through seed heads, it easily outcompetes the native plants in the area. Not only is this bad for native plant species, it is also an issue for animal life. Invasive phragmites creates dense stands of heavy stalks that inhibit water access for many species such as turtles, waterfowl and even mammals.

Invasive phragmites also poses serious problems to people as well. Because it grows so large and in dense stands, it can block views and take over previously usable spaces, significantly decreasing property values, and can restrict access to your land and water. The aggressive root system can actually send shoots up through pavement, ruining roads and driveways.

Invasive phragmites can also be a fire hazard, with massive amounts of dry stem and leaf material building up year after year. All it takes is a spark, and the entire stand can go up in flames, endangering nearby houses, property and people.

So, What Can I Do About It?

Although invasive phragmites is difficult to control, it is not impossible, but determination and persistence are necessary.

Getting rid of invasive phragmites can be a big task. The same stand may need to be dealt with for multiple years in a row. Engaging the assistance of professionals to help you with a control plan can make a big job manageable.

There are three main methods of control and using them together as part of a plan will be far more effective than trying to use one single technique. These three methods of control are chemical, mechanical and prescribed burning. What order you use them in and how effective the treatment will be depends on how well established the stand of phragmites is.

Chemical Treatment

Chemical treatment is generally the first method of control that is employed. This method uses herbicides to kill the plant. The two most common herbicides that are used on phragmites are glyphosate (Shore Klear, AquaNeat), and imazapyr, which are usually applied with backpack sprayers, but can be applied to small stands of phragmites through injection into the stems or hand-swiping on very small pioneer stands. Generally, herbicides are applied in late summer after the plants have bloomed (formed seed heads) but before first frost. This timing causes the plant to transmit more of the herbicide into the root system for a more successful control effort.

Assess the phragmites stand and take note of a few different details. First, what is the surface area that it covers? Calculating this accurately is important, so that you know how much herbicide you will need. Also pay attention to how thick the stand is. If you cannot walk through the stand to administer the herbicide, you may need to cut the stalks (mowing) for easier access to the entire field. Also take note of where the phragmites is growing. Is it in the water or on dry land? This may change the application process.

When you are ready to apply the herbicides, it is important to make sure that you minimize overspray, to avoid damage to remaining native plants or getting herbicide into the water.

Applying herbicide properly to a stand of phragmites is not a job for everyone.  If you are uncomfortable applying the chemicals yourself, you can contact us. Harrietta Hills is licensed in the state of Michigan and we are experienced and equipped to get the job done. Please feel free to give us a call for professional help at 877-389-2514 or email with your request for a consultation.

Permits may be required for some application locations. If you are in the state of Michigan, you can visit and select Aquatic Nuisance Control for state permits and more information.

Mechanical Control

Mechanical control is essentially the process of mowing the problematic area. You can use mowers, brush cutters, heavy-duty string trimmers or hand cutting tools to perform this task. Mechanical control is only effective when done in conjunction with herbicide application. Wait several weeks after herbicide application to give the herbicide plenty of time to be absorbed into the phragmites plants. Mowing will remove the dead stalks and promote native plant growth as well as making it easier to spot re-growth the following year.

Because phragmites reproduces through both rhizomes and seed heads, it is possible to accidentally spread the plant when you mow, so care should be taken. For small pioneer stands, bagging and properly disposing of the plant matter can stop the seeds from spreading and also allows sunlight to get down to the ground, allowing native plants to grow back.

When you are cutting phragmites in a wetland area it is often best to wait until winter when the ground is frozen. This can provide safer, easier access and can also make clean up simpler. Winter cutting also minimizes the impact on any existing native plants, as they are unlikely to be growing. It is NOT recommended to use mechanical control alone, as this stimulates the root system and causes even more vigorous re-growth by the phragmites which will make the problem worse over time.

Prescribed burning (EXTREME CAUTION recommended)

Prescribed burning of phragmites stands is generally a control method used by professionals after carefully developing a detailed burning plan. Burning should be done several weeks after chemical treatment, although less than a year after. Just like mowing, it is not recommended to use burning alone.

Although this method can be effective, safety of a burning operation can be a huge concern. Because mowing is an equally effective method of removing the stalks, burning should only be used when mowing is not an option and you can guarantee that the fire will not spread.

Fire can endanger lives and neighboring property and kill native plants and animals. If the patch of phragmites extends onto neighboring lands, there is no way to stop it from spreading and should be avoided.

And Finally

Be prepared to repeat the process! Invasive phragmites is extremely resilient, and although it is certainly possible to get rid of it, make sure to monitor the area for the next few years to make sure all signs of this plant are gone.

Never hesitate to contact a professional with questions or for help with your eradication efforts. Harrietta Hills can help you with invasive phragmites control in Michigan. Elsewhere there are many groups and agencies who are dedicated to eradicating invasive phragmites and may have resources that are more specific to your geographic area.