Snip, drip. Jane Moscowitch snipped a shoulder-high phragmites down to knee height. She crouched and dripped a few drops of purple-dyed herbicide into its hollow stem.
“Funny,” she said, “I got my degree in environmental science one year, and the next year I got my herbicide applicator’s license.”
Phragmites australis, sometimes known as the common reed and other times known as just phragmites or phrag, rarely gets this kind of close attention. You’ve seen this giant among grasses, even if you didn’t know its name or pay it much notice.
Its flower resembles a feather duster or a fluffy plume. The plant often grows to six feet tall, and sometimes to 15 feet. It grows in roadside ditches, in marshes, on the edges of ponds, lakes, rivers, and streams. Phragmites are graceful plants, but they can cause trouble.
Last July, Moscowitch, a conservation assistant with the Vermont field office of The Nature Conservancy, applied herbicide to protect an unusual ecosystem – a New England riverside seep – from phragmites, which are known to dominate the wetlands they invade.
Ankle-high plants are the usual stars of this riverside seep, where few other plants can survive the high calcium content of the water or the annual scouring of ice from the White River, rushing over rocks just steps away. The changing seasons find this riverbank in northern Windsor County, Vermont, dotted with pink, purple and white tiny flowers. Rare rushes and sedges, both grasslike plants, also find a home here.
But one grass is not welcome: phragmites. While most of the plants in this Nature Conservancy preserve are tiny, phragmites are giants. In the riverside seep, phragmites threaten to shade and crowd the rare plants out of existence and turn the rich, biological diversity of the seep into a place with no more variety than a well-manicured lawn.
Phragmites aren’t just a problem in this one Nature Conservancy preserve. Land managers of every type, from the federal government to private homeowners, are looking for ways to eliminate, or at least reduce, the grip this plant has on their land.
While conservationists have battled the plant for decades, it is only recently that they’ve learned important information about their enemy; while phragmites is native to North America, a highly aggressive and non-native variation of the plant was introduced to this continent from overseas. It is this introduced type of phragmites that invades wetlands and dominates them.
Scientists from New Hampshire and Vermont contributed phragmites samples to a study that found that all of the local samples were from the invasive strain. No native phragmites were identified in our area.
The discovery of several genetic types of phragmites has added complexity to the job of conserving wetlands. To start with, in the eastern United States, the native types of phragmites may be rare enough to be worthy of conservation themselves. Genetic identification is expensive and difficult, so a Cornell scientist created a checklist of 15 physical traits that, when taken together, are remarkably accurate in determining whether a particular phragmites plant is native or introduced.
Native phragmites have stems that are smooth and shiny, bend easily, and are reddish at the bottom in spring and summer. Their flowers are sparse, and the plants don’t grow close to each other. The introduced type has stems that are rough and ridged, resist bending, and tan at the bottom. Their flowers are full and the plants grow densely.
The discovery of the different genetic types of phragmites has also slowed research into possible biological controls. The biological control for an invasive plant is usually an insect which is so hungry for the shoots or leaves or seeds (or in phragmites’ case, rhizomes) of that particular species of plant that they slow or stop the plant’s spread while leaving other plants alone.
Conservationists are eager for a biological control for the non-native strain of phragmites because, once established, the plants are difficult to get rid of. A favored technique for large stands is to apply herbicide and then burn the area to clear the way for native plants. Few land managers are as lucky as The Nature Conservancy of Vermont, which discovered its phragmites problem when the plants were still sprouts, thanks to the sharp eyes of Sara Hand, a volunteer preserve steward.
But while some moths and flies have been found that look promising for the control of phragmites, the insects must now also prove themselves harmless to the native types. That research will take time.
Meanwhile, The Nature Conservancy of Vermont will continue to apply herbicide, drop by drop, in their riverside seep preserve to defeat the phragmites while safeguarding the rare plants nearby. And the invasive genetic type will continue to spread to new areas, now unmasked as a nonnative wetland invader.