Introduction & History

Invasive phragmites (Phragmites australis, P. australis ssp. australis), also known as common reed, is a non-native, perennial wetland grass species that can grow 15 feet or more in height.
The name phragmites is derived from the Greek word phragma, which means “fence” or “barrier.”
Invasive phragmites may have been introduced to the eastern United States (US) in the late 18th or early 19th century. It likely arrived through multiple pathways, including ballast water from ships, contaminated agricultural products, shipping crates and packaging, and intentional planting for ornamental or erosion control purposes. Phragmites was sometimes used as stuffing material for mattresses, cushions, and pillows due to its resilience and availability.
The specific timeline and means of introduction of invasive phragmites are not well documented, but historical records suggest that its spread accelerated throughout the 20th century, particularly as human activities such as land development, alteration of hydrological regimes, and nutrient enrichment of wetland habitats created favorable conditions for its establishment and expansion.
Today, the Long Island Invasive Species Management Area (LIISMA) focuses on managing small infestations of invasive phragmites at coastal plain ponds and streams to protect some of the highest concentrations of rare species and ecological communities in New York State.

Identification & Biology

Invasive phragmites can reach heights of 15 feet or more.  Invasive phragmites stems are stout, hollow, and cylindrical, with a smooth surface. They are usually tan to light brown in color and may have a purplish tinge at the base. The leaves are long, narrow, and taper to a point. They are typically bluish-green in color and have a rough texture. The leaves grow alternately along the stems and may have serrated edges. Invasive phragmites produces large, dense seedheads at the tips of its stems during the flowering season. The seedheads are feathery and have a purplish-brown color.
The species spreads primarily through underground rhizomes, which are thick, fleshy, and horizontally creeping. Rhizomes give rise to new shoots and allow phragmites to form dense stands. Seed production occurs in late summer, with seeds dispersed by wind or water. Phragmites typically colonizes wetland habitats, including fresh to brackish marshes, swamps, ditches, wet fields, disturbed sites, and along the edges of ponds, lakes, streams, and rivers. The species is tolerant of a wide range of environmental conditions, including salinity, fluctuating water levels, and soil types. It can colonize disturbed areas and thrive in both natural and human-modified landscapes. Invasive phragmites can be distinguished from native phragmites (Phragmites americanus, P. australis ssp. americanus) by their stems, leaves, leaf sheaths, and stands. Native phragmites has flexible, smooth, shiny, reddish or purplish stems. Invasive phragmites has rigid, rough, dull, tan stems that are hollow inside. Native phragmites has yellow-green leaves, while invasive phragmites have blue-green leaves. Native phragmites stands are less robust and appear as scattered stems in a biodiverse wetland community, while invasive phragmites stands are often large, tall, and extremely dense. One of the distinguishing features between invasive phragmites and native phragmites is the persistence of leaf sheaths on the old stems through the winter in the invasive species, even after the leaves have died back. This can give the plant a distinctive appearance, with a dense layer of dried leaf sheaths covering the lower portions of the stems. In contrast, native phragmites generally shed its leaf sheaths from the older stems during the winter, leaving the stems relatively bare. Genetic markers may also be considered when distinguishing between invasive and native phragmites populations.

Damage & Concern

The rapid spread and dominance of invasive phragmites in wetland ecosystems can have detrimental effects on native biodiversity by outcompeting and displacing native species and degrading wetland and aquatic communities. The displacement of native species can lead to a cascading series of negative impacts on other organisms dependent on native species and their shared habitats.

Invasive phragmites outcompetes and displaces native phragmites. The native species is considered rare in the LIISMA region and other areas of the eastern US, largely due to competition with the invasive species, which has become widespread and dominant in many wetland habitats.
The dense root systems of invasive phragmites can alter the hydrology of wetland ecosystems by impeding water flow and reducing water levels. This can negatively impact the hydrological functions of wetlands, including water quality, flood control, and habitat suitability for wetland and aquatic organisms. 
Dense stands of invasive phragmites can create physical barriers that block fish passage, particularly in narrow streams and waterways.
Invasive phragmites can obstruct recreation areas, such as boat launches and fishing docks, and can cause safety hazards. Large stands of phragmites can block scenic views, fire hydrants, and right of ways.

Invasive phragmites presents a complex ecological issue. On one hand, its rapid spread and dominance in wetland ecosystems can have detrimental effects on native biodiversity. On the other hand, invasive phragmites can offer some benefits, particularly in mitigating coastal erosion. Its dense root systems and tall stalks can help stabilize soil and reduce the impacts of wave action along coastlines. In areas where erosion is a significant problem, this trait can be seen as advantageous, especially in the context of human-induced climate change leading to rising sea levels and increased storm intensity. It is important to weigh these benefits against the broader ecological consequences of this invasive species.
Management

Prevention and Early Detection and Rapid Response (EDRR)

Prevention and EDRR strategies can be effective tools for managing invasive phragmites. 
Prevention includes education and outreach to raise awareness about the impacts of invasive phragmites and promote responsible behavior among landowners, recreationists, and other stakeholders. The implementation of best management practices (BMPs) can prevent the establishment of invasive phragmites in vulnerable areas. BMPs focus on minimizing adverse habitat disturbance and avoiding activities that could spread invasive phragmites seeds or fragments to new areas. Regulations and enforcement related to the importation, sale, and transport of invasive phragmites can help prevent accidental introductions. Invasive phragmites is a prohibited invasive species in the state, meaning it cannot be knowingly possessed with the intent to sell, import, purchase, transport, or introduce. In the past, invasive phragmites may have been inadvertently transported to new locations on ponds and waterways from equipment or materials used in the construction and maintenance of waterfowl blinds. New state regulations prohibit the use of phragmites or other invasive plants for covering hunting boats and blinds.

Management & Control

Cultural Methods:

High nutrient levels can favor the growth of invasive phragmites over native plant species, giving invasive phragmites a competitive advantage. 
Septic systems and runoff from urban or agricultural areas can introduce elevated levels of nutrients, including nitrogen and phosphorus, into waterbodies and stimulate the growth of invasive phragmites and other wetland and aquatic invasive species. 
Lawn fertilizers and pet waste can contribute to nutrient pollution in waterbodies. Choose fertilizers that are labeled as “phosphorus-free” or “low-phosphorus.” Follow proper application rates and avoid fertilizing before heavy rainfall or during periods of high water runoff to minimize the risk of nutrient runoff into waterways. Managing goose populations according to federal and state regulations can reduce nutrient pollution and minimize the impact of high populations of geese on water quality. Maintaining a native plant buffer around waterbodies can reduce nutrient pollution and reduce the growth of invasive phragmites and other wetland and aquatic invasive species. This method involves planting or maintaining native vegetation along the banks of waterbodies to filter pollutants, stabilize soil, and provide habitat for native wildlife.

Spading:

Manual and light mechanical control methods, such as spading and underwater cutting, can be effective for managing small or sparse populations of invasive phragmites. 
Spading involves cutting phragmites below the surface at a 45-degree angle with a garden spade and removing the plant. Spading can be used on land or in water and can be done several times during the growing season as new shoots emerge. 
The best time to cut phragmites is July through August. Cutting phragmites before it flowers and sets seed can help prevent the spread of seeds and reduce the potential for further infestation. 
If spading can only occur once per season, the best time to cut is when the plant approaches peak height, as this depletes more stored nutrients and energy in the belowground structures. Repeat spading until the phragmites is eliminated, which could be three or more years.
Spading is time-consuming and most effective on small or sparse populations (for example, <1,500 stems).\

Underwater Cutting:

Underwater cutting involves cutting phragmites stems below the water as low as possible, thus cutting off their oxygen supply and drowning them. A raspberry cane cutter is an effective cutting tool for sparse populations. Repeat underwater cutting until phragmites is eliminated, which could be three or more years. Underwater cutting is time-consuming and most effective on small or sparse populations (for example, <1,500 stems).

Herbicide:

The control of invasive phragmites using herbicide involves the targeted application of herbicide to actively growing plants to effectively suppress or eliminate their growth. Wicking or wiping applies herbicide directly to the leaves and stems of phragmites using a specialized wick, glove, or sponge applicator. A wick applicator consists of an herbicide reservoir attached to a wiper made of an absorbent material such as cotton rope, towel, carpet, or sponge. A glove applicator involves wearing a cotton glove over a waterproof glove, saturating the cotton glove with herbicide, and then wiping the herbicide onto the plant’s leaves and stems. These methods allow for precise targeting of herbicide to phragmites while reducing the risk of herbicide drift or contamination of surrounding vegetation. The judicial and targeted use of herbicide minimizes soil disturbance, which can be beneficial in delicate ecosystems where soil stability and integrity are important for ecosystem function. Avoiding soil disturbance preserves soil structure, minimizes erosion, and maintains habitat for soil organisms and native wildlife. Select an herbicide formulation labeled for phragmites control and approved for use in wetland environments within the state and relevant county or local municipality. Common herbicides used to control phragmites include aquatic formulations of glyphosate and imazapyr. 

Herbicide application is most effective when phragmites is actively growing, typically during the late summer or early fall. Applying herbicide during this period ensures maximum uptake and translocation of the herbicide into the plant’s vascular system.
Herbicide control may need to be repeated for at least three years. Follow all label instructions and applicable regulations to minimize environmental impacts and ensure safe and effective herbicide application. In most cases, herbicides can only be applied by a certified pesticide applicator.

Smothering/Tarping:

Using thick black plastic to cover cut phragmites during the growing season can be an effective method for limiting regrowth, especially in small-scale infestations. Depriving the plants of light and increasing temperatures beneath the plastic can effectively kill phragmites and prevent regrowth. 
Smothering/tarping is most effective in small areas exposed to direct sunlight, where the logistics of covering the cut phragmites with plastic are manageable. For larger populations, consider covering the outer areas of the population and gradually over several years moving toward the center of the population.
While effective at controlling phragmites, covering cut phragmites with plastic may also eliminate native wetland species under the tarp. This can have ecological implications for biodiversity and ecosystem function, particularly in delicate ecosystems.

Cutting;

Cutting invasive phragmites in July or August, when most of the food reserves produced that season are removed with the aerial portion of the plant, can reduce the plant’s vigor. This may suppress or eventually eliminate a population if carried out annually for several years. Care must be taken to remove cut shoots to prevent their sprouting.  

Monitoring & Reporting 

Regular monitoring and follow-up treatments are necessary to ensure and assess the effectiveness of management and address any regrowth or new infestations. Monitoring tracks changes in vegetation composition and habitat conditions over time, allowing for adaptive management and refinement of management strategies. Identify and monitor wetland areas that are ecologically significant and relatively free of invasive phragmites. Use the iNaturalist and iMapInvasives apps to monitor and report phragmites and other invasive species. iMapInvasives can track management activities.
The likelihood of success in controlling phragmites by any method drops significantly as the population size increases. Focus on controlling relatively small, emerging infestations to protect high-priority conservation targets. State and local permits are required to control phragmites in regulated wetlands.