A number of different control techniques have been utilized to combat phragmites with varying degrees of success; digging, mowing, burning, flooding, grazing, and treatment with a number of different herbicides. Although many prefer to avoid the use of chemicals, herbicides provide the most effective primary method of control, particularly when coupled with non-chemical methods that will further stress the plant. Because phragmites has deep and extensive root systems, digging is not effective except for the very smallest infestations. Mowing early in the season will actually increase stand density, although later in the season, it can help deplete energy reserves. Flooding cut stems can be effective but is not feasible in many settings. Prescribed fire can increase the growth and vigor of phragmites but is a useful tool in conjunction with herbicide, as it clears away thatch and allows the seed bank to respond. Phragmites control is a long-term endeavor; any treatment plan should include provisions for long-term monitoring and re-treatment of new shoots as needed. Since beginning control efforts early in the invasion process is easiest, likeliest to result in eradication and most cost effective, it is imperative to catch non-native phragmites just as it begins to invade. Unfortunately, this is when it most resembles the native form. In planning control efforts, it is critical to first determine that the population in question is actually the invasive subspecies, rather than the native. Non-native phragmites can appear sparse while it is just beginning to invade, but a few characteristics can help to distinguish it from the native:
- It retains the tan leaf sheaths on its lower stems-those of the native fall off easily, exposing its stems which turn reddish in the sun;
- It usually doesn't produce seedheads until it is well-established and the population is much denser;
- It is a bluish gray-green, while the native is a brighter, yellower green;
- Native phragmites can grow densely where there is nutrient enrichment but its reddish lower stems will still be exposed. (click here for more info)
A brief discussion of factors that should be considered in planning a phragmites control project follow, along with links to more detailed references elsewhere. Topics include:
- Permit information
- Herbicides-advantages and disadvantage of the most commonly used chemicals
- Herbicide Labels and why you should read them carefully
- Planning a control effort
- Permit and planning information from MDEQ
- Phragmites control resources on other websites
- Invasive species control methods (general)
- CDMS database - Herbicide Labels and Material Safety data Sheets
An Aquatic Nuisance Control permit is required to treat phragmites with herbicide anywhere below the ordinary high water mark along the shorelines of the Great Lakes and Lake St. Clair. Also, a permit is required to treat phragmites using herbicides for most inland settings, if the plants are in standing water at the time of treatment. The MDEQ's Water Bureau has created a general permit category for this type of activity, which allows property owners to request authorization for control of invasive or non-native species through a simplified permit process for a reduced application fee. Applications for single-season Aquatic Nuisance Control permits must be postmarked before August 15 in the year of the proposed chemical treatment.
A separate Great Lakes Shoreline Management permit is required to mechanically remove phragmites (cutting and mowing) in conjunction with herbicide treatment below the ordinary high water mark of the Great Lakes and Lake St. Clair. The MDEQ's Land and Water Management Division has created a general permit category for this type of activity, which allows property owners to request authorization for control of invasive or non-native species through a simplified permit process for a reduced application fee. These permits are effective for up to five years. (Click here for MDEQ links)
Two chemicals are commonly used to treat phragmites; imazapyr and glyphosate, and both must be used in a formulation that is specifically approved for use in wetlands. Habitat® is the only formulation of imazapyr that is presently approved for wetland application. Wetland approved forms of glyphosate, in contrast, are available in a number of different products including Rodeo®, Aquamaster®, and AquaNeat®, to name a few. Glyphosate-based products can be used by individual landowners on their own property, although certification or other training is recommended.
Both imazapyr and glyphosate have advantages and disadvantages: imazapyr is more effective overall, but it stays active in the soils for a longer period of time and because of this, generally kills off any natives in the area, too. Untreated desirable plants can be affected by root uptake of imazapyr from treated soil. Sites that are treated with imazapyr should not be seeded or planted for a year following treatment. If treated vegetation is removed from the site, it should not be used as compost or mulch around desirable species. Imazapyr can only be used in wetlands by certified or licensed aquatic pest control applicators, according to the federal label.
Glyphosate is much less expensive and does not persist in the soil. It should only be used in late summer or fall, after the phragmites has produced seedheads. It can still provide effective control of phragmites, and if a native seedbank is present, it will usually still respond. Both chemicals will kill any other plants that they touch-in areas where valued species are present, proceed with extreme caution (see link to table and herps and Phragmites). Some glyphosate-based products' labels includes hand-swiping as an approved application technique. Use of approved adjuvants may increase the effectiveness of both herbicides-see the product label for details, although may have adverse impacts to amphibians.
All herbicides must be used in accordance with their product labels, including the use of personal protective equipment. Labels carry the force of federal law and provide valuable information on a number of topics that will ensure safe and successful use including:
- Application Rates and Techniques
- Restrictions on use including precautions for potable water intakes
- Wind, temperature and humidity conditions under which the herbicide can be applied safely
- Precautions for managing off-target impacts on desirable plants
- Adjuvants, including approved surfactants
CDMS maintains an online database that includes informative Labels and Material Safety Data Sheets for all herbicides. It can be searched in a number of different ways. (click here for links).
Planning a Control Effort
A successful control effort begins with a well-thought out plan of attack. Elements of a plan should include:
- A map of the phragmites in the area; note age and density of stands, and identify of any native stands
- An inventory of any high value features, including rare plants, animals or communities that may require special protection
- An inventory of site conditions, include sources of nutrient or road salt run-off, fill dirt, and other invasive species that might be targeted simultaneously
- Coordination with other landowners
- Treatment plan, including techniques to be used, herbicide, any adjuvants, timing, etc.
- Ideally, some method for removing dead phragmites, whether by prescribed fire or mowing
- A monitoring plan
- Designated resources for treatment of any resprouts or new infestations
Permit and Planning Information from MDEQ
- Control and Management of Invasive Phragmites
- Control of Phragmites Under the General Permit for Limited Great Lakes Shoreline Management Activities
- FAQ-Chemical Treatment of Phragmites
- Aquatic Nuisance Control Permit Application
- Shoreline management - with links to permit applications for mechanical removal of phragmites after herbicide treatment
Phragmites Control Resources
- Information for Landowners - A Landowner's Guide to Phragmites Control. For hard copies of the brochure contact the Office of the Great Lakes at 517-335-4056.
- Information for Resource and Land Managers - A Guide to the Control and Management of Invasive Phragmites
General Invasive Species Control Methods
- The Nature Conservancy - Weed Control Methods Handbook: Tools and Techniques for Use in Natural Areas
- Wisconsin Manual of Control Recommendations for Ecologically Invasive Plants