Phragmites—Monster Weed of the Wetlands!

Q: Mike: we are greatly concerned about the invasive grass Phragmites on our northern beaches of Lake Michigan. The local powers-that-be are talking heavy-duty chemical removal; are there any organic options?

---Sally in Northport, Michigan

Mike: I have a small second home that backs up to a tidal glade. What can be done about the very insistent Phragmites? I've tried various sources looking for useful information, with no results and am hoping you can help. Thank you!

---Rhodie in Lewes, DE

A: Well, Rhodie, it turns out that some of the most intensive study of this invasive monster is being conducted in your very own backyard! Most of the information in this week's answer comes courtesy of Jack Gallagher, Ph.D. and Denise Seliskar, Ph.D., co-directors of the [deep breath now] Halophyte Biotechnology Center at the University of Delaware's College of Marine and Earth Studies in Lewes (which is pronounced "Lewis", and not "Lou's", by the way), Delaware.

They explain that Phragmites is a VERY interesting plant. Although once considered an alien invasive, we now know that the same species that's become such a problem in modern North America was here ten thousand years ago, thanks to analysis of the prehistoric scat of a giant sloth. (That's the organic answer—bring back the sloth!)

The Dueling Doctors of Delaware add that the plant is native virtually everywhere in the world; and is highly valued in Europe, where it has been used to create the absolute finest thatched roofs for untold centuries, and the Fertile Crescent, where it served many purposes, including the making of paper. But it's dying out there while becoming a huge problem here. In other words, the people who want it can't keep it alive, and we who don't want it can't keep it dead. (THAT, ladies and gentlemen, is gardening on a stick.)

The problem here is that this massive plant—heights of 14 feet are not uncommon—is a big bully. It gravitates to marshy areas—the wetlands so essential to the survival of just about everything—and actually changes the neighborhood. From a human perspective, Dr. Gallagher explains that it often ends up blocking the ocean or sunset view that led a homeowner to live there in the first place. In the ecosystem it invades, its dense underground rhizome system actually raises the topography, eliminating the puddles and small pools of water so essential to fish, amphibians, turtles and waterfowl. And University of Delaware plant biologist Harsh Bais Ph.D., has recently shown that it is also strongly alleopathic. Like the legendary black walnut, Phragmites secretes a naturally occurring compound that interferes with the growth of many other plants.

There are many theories as to how this plant—also known as "common reed"—got so out of control over here, but the good Doctors name disturbance associated with development as the most commonly accepted. When areas are drained for building, dredging takes place to save a beach, or other things are done to previously natural areas, it becomes more dominant than the non-aggressive native sub-species and other coastal plants.

OK, now the control options:

Repeated cutting. As with running bamboo, repeated cutting of the green growth above ground will eventually exhaust the root system. Yes, this takes years to work, but so do chemical herbicides, making mechanical removal the ecologically sound choice and quite possibly the most cost effective one as well.
Drown the bum! If the plant is growing in water and you can cut it below the water line and keep the cut area submerged, the root system will suffocate within days, explains Dr. Gallagher, as the plant relies on its stems, living or dead, to convey oxygen down to the roots. If the stems can't breathe, neither can the roots.
Corral it with a living fence. Get back here! Dr. Seliskar says she now regrets this choice of words, as the study in which she took part in New Jersey didn't use an invasive like the famed Multiflora rose as the fence. Instead, she and her colleagues used native plants—shrubs, grasses and rushes—that grow naturally in between marshy and upland areas to stop the advance of Phragmites. Because this pestiferous plant generally marches from the land to the water, using the right plants—or installing the same type of rhizome barrier used to contain running bamboo—can keep it out of those delicate areas and on land, where you can more easily repeatedly cut it. Here's a one to an excellent brochure by Dr. Seliskar on general Phragmites control.
Graze it to death! This idea comes from another source; an excellent case study from the New Jersey Division of Fish & Wildlife published in the Spring, 2001 issue of Conservation magazine that reports on the successful use of sheep, goats and even cattle to control the plant.

Q: Mike: We are plagued with the weed PHRAGMITES in our garden. Can we use the same advice you've provided for eliminating Running Bamboo, since both plants spread by rhizomes? Love your show,

--Sallie & Steve in Ocean View, DE

A: Absolutely! Click here to review all those bamboo options in a previous Question of the Week. And let me add this final caution: Do not let those beautiful plume heads form! Prized by dried flower arrangers, those huge plumes are filled with seeds that are spread by the wind. And while the Doctors of Delaware stress that the rapidly advancing rhizomes are the biggest threat, these seeds also spread the problem plant to new areas. Hey—maybe that makes this beast even worse than bamboo!

Ask Mike A Question Mike's YBYG Archives Find YBYG Show