Controlling Phragmites in a Lake or Pond: Everything You Need to Know

Controlling Phragmites in a Lake or Pond: Everything You Need to Know

Did you pay good money for that lakefront property with that breathtaking view? Has it turned into a reed forest?

Were you looking forward to a serene pond full of friendly fish? Has your little pool of paradise turned into a stagnant graveyard?

Members of an invasive genus known as Phragmites are often the culprits behind these and other plagues on homeowners who want nothing more than to enjoy their various waterscapes.

If you're growing desperate for effective ways to control phragmites, then keep reading. We're here to help!

What Are These Phragmites and What Do They Do?

Phragmites (pronounced "frag-MY-teez") is a genus of perennial aquatic reed grasses that are extremely common inhabitants of the world's temperate and tropical climate regions.

Four species make up the Phragmites genus:

  • Phragmites australis
  • Phragmites japonicus
  • Phragmites karka
  • Phragmites mauritianus

P. Australis

The species that is most likely to be the cause of your waterscape woes is Phragmites australis.

The P. australis has stems that can grow up to 15 feet tall. They feel slightly rough, and they don't have fungal spots (although you may find some mildew on them).

The leaves are blue-green, and they're darker than native varieties of phragmites. They are elongated, typically reaching up to 1½ inches wide, and their sheathes cling to the stem and remain over the winter.

P. australis also grows flowers that tend to be purple or golden. They typically grow in loose, branching clusters.

The Good, the Bad, and the Ugly

Now, P. australis isn't all bad. Or ugly.

For instance, in their native environments of Australia, Europe, and Asia, phragmites form an essential part of the habitats of various bird species, such as bearded reedlings, reed warblers, crakes, various types of bittern, and grassbirds.

P. australis is also one of the most commonly used grass species in what's known as phytoremediation water treatment.

Furthermore, reeds of the Phragmites genus are widely used as roof thatching. They have also been used for thousands of years in the Middle East to make musical instruments and a particular type of pen (the "qalam") used for writing Arabic calligraphy.

But despite its utility, P. australis is what's known as an invasive species due to its aggressive growth patterns. Put simply; they're everywhere—they've invaded every sort of wetland environment in the US.

Invaded? Yes! In addition to being invasive, P. australis is also non-native to the US. Experts have theorized that P. australis first came to the Americas in the 1700s. The reeds were commonly used as packing material for cargo on ships.

When this packing material was discarded, the broken stems were able to reproduce in the harbors and bays of New York and Boston. It didn't take long after that for them to become dominant.

It has also been determined that the high winds generated by hurricanes and tropical storms have played a major role in spreading these phragmites even farther afield over the decades.

But aren't different grasses and plants good for an aquatic environment? Generally, yes. So what is it about P. australis that's so destructive?

Everything. Seriously, it's as if it was designed to be the Terminator of your native species.

First of all, it is highly adaptable and tolerates up to mesohaline (brackish) levels of salinity. It also prefers still or slow-moving water. That basically makes your lake or pond prime real estate.

They shed their wide lower leaves, which leads to the formation of a thick layer of litter that blocks sunlight from getting to the other, native forms of vegetation that are nearby, preventing their growth.

This thick mass of dead foliage also makes life significantly harder for fish, waterfowl, and other wetland creatures like beavers and deer. It can impede their movement and compromise their water supply. And when these mats of plant matter dry out—which can combust very readily—they pose a very real risk of starting or sustaining wildfires. This is also the case for entire stands of these phragmites when they lie dormant in the spring, winter, and fall.

Since starving their neighbors of sunlight isn't quite enough to kill them all, P. australis also secrete chemicals that further inhibit the growth of any nearby would-be competitors.

They are also pollinated by the wind, which has allowed them to interbreed with other non-native varieties (they don't hybridize with native varieties). This has led to the formation of a sort of P. australis nightmare Hulk that is significantly stronger and more aggressive than native species. The wind also easily carries the millions of seeds they produce a year, along with broken fragments (that can reproduce vegetatively), wherever it blows.

To add insult to injury (murder, really), P. australis simply are not able to house native reptiles, amphibians, and marsh-nesting birds. They are also only able to support far lower numbers of the types of insects that aerial foraging birds and native wetland plants feed on.

They also play havoc with the hydrology of the places in which they've set themselves up. P. australis is a very thirsty plant, and its high levels of water consumption can lower water levels in entire areas of wetland. Furthermore, their thick stems and the dense formations in which they grow can interfere with the normal flow of water and even clog drainage ditches.

Other hazards posed by thick, aggressive stands of phragmites are their ability to block points of access and essential services like fire hydrants. This compounds the potential damage done by their flammability. They can interfere with buildings' foundations and other concrete surfaces as well.

People can even become lost in stands of phragmites that have grown densely enough, which has the potential to lead to loss of life if it occurs in harsh enough weather conditions.

So, how can you fight back against this juggernaut of a plant species and reclaim your lake or pond?

The Best Way to Control Phragmites

Consistent, long-term treatment is necessary to control phragmites effectively. The following regimen should be followed for up to three years, and it may require additional follow-up beyond that.

Pre-Treatment Mow (Summer)

This optional step should precede any herbicidal treatments by around 6 to 8 weeks. On their own, any efforts at the physical removal of phragmites will enjoy only limited and temporary success.

However, this phase of the plan will remove any dead tissue, thus allowing the herbicides that are soon to follow a greater area of contact with living phragmites tissue.

This removes what might otherwise act as a shield against herbicides. Some points to consider for this step:

  • Fallen stem sections can begin to develop roots and regenerate, so they should be contained as well as possible in areas where there is a possibility that they might start a fresh population elsewhere
  • You should explore what options are available to you regarding the disposal of cut material

Herbicide Treatment (Fall)

The only herbicide that is recommended for use against phragmites and that doesn't need a certification to apply is aquatic glyphosate. This type of herbicide attacks the plant's roots. It is also effective against other annoyances like cattails, bulrushes, water lilies, and other grasses.

Note that aquatic herbicides like glyphosate are much more effective when used in conjunction with a surfactant.

Main Mow (Winter)

At least a month after the previous season's herbicidal treatment has done its job, any dead plant matter should be knocked down, pulled up, and removed in order to prepare for the next season's treatment.

Instead of mowing, it may be appropriate to burn or trample dead tissue during this phase.


Efforts at reintroducing native species of vegetation may be necessary. You should take such steps only if native vegetation has not begun to re-establish itself after the above regimen has been completed. You should also ensure that control over non-native phragmites has been established.

Some Tools to Help Get the Job Done

The following offerings from Weeders Digest are among some of the most helpful tools for use during the mowing phases of the control strategy outlined above:

The End of Your Phragmites Nightmare

Congratulations! You now know what you're dealing with and how to deal with it! But are you ready to finally reclaim your lake view? Will you be the one to help the home team reclaim your pond or other wetland property?

Contact Weeders Digest now so we can make it simple and convenient for you to control phragmites!

28th Jul 2021 Weeders Digest

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