The debate over using weed-killer on Lake Michigans reeds
By Anne Stanton 8/17/09
When you get put on hold at the Watershed Center of Grand Traverse Bay, youll hear bits of environmental advice such as avoiding lawn fertilizers near the bay.
But now the environmental group is supporting a plan to put Rodeopretty much the chemical equivalent of the weed-killer Roundup into Lake Michigan in order to kill a reed called phragmites (frag-MIGHT-eez).
You can see patches of the 13-foot reeds swaying in shallow water from Northport to Charlevoix. Unlike the native phragmites that have been here for thousands of years, this European exotic plant arrived in the Atlantic seaports sometime in the early 1800s, according to research by Kristin Saltonsall of Yale University.
Unlike the native phragmites, it pushes out native vegetation and ultimately becomes such a thick mass, its inhospitable to other living creatures, said Brian Piccolo, a wildlife habitat biologist who is anxious to get rid of the reed before it spreads.
Phragmites is new to the area and often takes root where the dirt has been disturbed from construction or on newly-exposed shoreline. Some believe that the die-off of zebra mussels is creating a rich bed of nutrients that phragmites need to thrive.
The Department of Natural Resources has received a $120,000 grant for contractors to spray herbicides on the affected shorelines, beginning in late August when the plant is most porous. Next year, it will spend $50,000.
There are no plans for an aerial spray; it will be mostly applied by contractors wearing backpacks of the herbicide, or hand swiped where endangered plants thrive. Although the Watershed Center has endorsed the spraying, the staff feels conflicted.
For us, this isnt a comfortable place to be. We dont like to use herbicides. We want to make sure its done early, so we use less herbicide, and to use it comprehensively to get the infestation quickly under control, said Ellen Kohler, the Watershed Centers policy analyst. But were not out there advocating herbicides as a general matter.
John Nelson, the Baykeeper of the Watershed Center, owns a Northport cabin where phragmites has taken root. He says it has pushed out native plants to the detriment of the birds and insects that depend on them.
Im not too concerned about the cosmetics if you will, or how it blocks the view. For me, its more of a habitat issue. It becomes a monoculture. I think the shoreline is better off if it has the various indigenous plants growing in harmony. Over a long period of time, nature has a tendency to balance it out and the phragmites will recede. Short term, we need to control the plant.
But the plan to use Rodeo has led others to speak up, believing that Rodeo will either fail in the long run or hurt nature in unintended ways.
To turn around and add more poisons to an already damaged environment by calling these plants invaders and deluding ourselves of the botany and biology of the situation strikes me as criminal actually, said Jim Moses, an organic farmer in Leelanau County. We have a feeling of dominance over others, over creation that I dont feel is justified. I see no place in using toxins that we dont understand very well. Have we not learned the lessons of Silent Spring (a landmark book by Rachel Carson written in 1962, revealing the impact of DDT)? Its time for a more open debate. Ive been very frustrated that everything has been planned in one voice with no room for dissent.
In nature, everything has a role, and the function of phragmites is to suck up the excess nutrients along the shoreline. If you kill the plant, then the nutrients that the plant is taking up into biomass will go unimpeded into Lake Michigan, Moses says. That might prove toxic to some species or alter conditions to favor more opportunistic creatures. Im not saying I know the consequences. My concern is, in our attempt to eliminate this plant, which is flourishing, we might have unforeseen consequences. The advocates of the poisonous path say its nailed down science, but its not as nailed down as people want.
Moses questions whether native grasses will grow in place of the phragmites and disputes that the reed is inhospitable to other species. He cites a study by Richard Kane on the New Jersey Audubon Society website. Kane listed 33 birds that nest, breed, take cover, and hunt fish in phragmites swamps or marshes.
But Kohler said that management of a marsh is entirely different than a lake shoreline. What I do know is that the diversity of birds and insects that thrives in an invasive species is much, much lower than what depends on native habitat. Do you wait and study everything, and then end up with a huge problem and an expansive change to our shoreline?
What a homeowner might regard as unwelcome vegetation is regarded by the DEQ as habitat for fish, birds and wildlife. For that reason, beachfront owners must obtain the states permission before making changes to the waterfront, whether its putting in a break wall or disturbing vegetation.
Thats why Mary and Mike Forness who live on East Grand Traverse Bay have been unfazed by the plants and trees that now inhabit their once sandy beach. It all began about 10 years ago, when the water level receded.
Gradually the waters edge was filled by a thick mix of trees, cattails, bushes, and phragmites.
Mary said she was willing to live with it because she didnt want to disturb the ecosystem. Thats why she was surprised to receive a survey letter from Acme Township regarding the chemical treatment of phragmites.
Forness said she had a lot of questions, and went to a recent Acme Township meeting where Kohler made a presentation.
Just dumping something into our bay where we swim, that alarms me. But everyone at the meeting said, Were okay with it, well send in our survey. But I think, Really? Dont you want to know whats in the herbicide? What surprised me was that it seemed to be a done deal. It seemed like they had already made the decision to use Rodeo and another herbicide and that they were just waiting to complete the survey before going with it.
Yet Forness had a lot of questions, including whether the herbicide was a threat to humans or aquatic life.
The active ingredient of Rodeo is glyphosate, which kills plants, but has not been found to harm fish or birds. Its an eye irritant for humans, and lethal if swallowed in large quantities.
But theres a little known wrinkle to Rodeo.
For maximum effectiveness, the label requires the addition of a surfactant -- a detergent that strips the surface of a leaf and allows glyphosate to enter the plants stems and leaves. But many common surfactants are lethal to fish and frogs, according to research by Rick Relyea, an associate professor and director of the Pymatuning Laboratory of Ecology.
A surfactant is used to cut through the waxy surface of a plant. The waxier it is, the harder it is for the glyphosate to get in. If you waxed your car and it rained, the rain would roll right off. Glyphosate on waxy leaves works the same way. Without a surfactant it would roll right off the leaf and never get into the plant, he explained.
Unfortunately, fish have cell membranes made of lipids or fats and the surfactant, which is really good at dissolving waxy leaves, is also good at dissolving the lipids on the gill cells. Surfactants make gill cells burst and the fish suffocates. So a surfactant that is good at killing plants is inherently also good at killing fish and tadpoles.
In a pond study of 25 species, including insects, snails, and tadpoles, Relyea found that Roundup (which contains glyphosate, the same as Rodeo) caused a 70 percent decline in amphibian diversity and an 86 percent decline in the total mass of tadpoles. Although spring peepers were unaffected, leopard frog tadpoles and toad tadpoles were nearly eliminated.
His research tested a popular surfactant of glyphosate called polyethoxylated tallowamine, which was fatal to tadpoles.
Surfactants dont have to be tested by the EPA -- theyre not regulated, and they never have been. They are categorized as an inert ingredient, which means their identities are kept as trade secrets and they dont have to be tested, Relyea said.
Surfactants are even lethal when used in lower than recommended doses and in the presence of soil, a follow-up study showed.
Nelson, who knew of the deadly effect on amphibians, said that the licensed applicator will not use a surfactant in Leelanau County on phragmites, which does not have a waxy leaf.
However, a surfactant will be used in other areas, as it was used at Beaver Island, said Piccolo, who didnt know what surfactant will be used.
Relyea said another drawback is that Rodeo isnt selective. It kills every plant it touches.
Will you kill both invasive plants and native plants? Its hard to know. If you apply the herbicide to a few test areas, youll have a better idea than if you apply it broadly. Try a few areas and see what plant species come back next spring, he said.
Kohler said the application is far more focused with a backpacker directly spraying the reeds, as opposed to an aerial application. But she also added that not all vegetation is necessarily good. Besides phragmites, there are other invasive plants that should be eliminated, including knapweed, narrow leaf cattail, and red canary grass.
The DNR said theyd be thrilled if these went away, too, she said.
Pam Grassmick said the potential downside of surfactants makes it imperative that the herbicides are professionally applied. She has overseen a three-year control effort on Beaver Island, which is being used as a model for the Grand Traverse region.
Grassmick, like everyone else confronting the problem, went through an intensive education process. Burning phragmites doesnt work, and neither does pulling the reed. Floating pieces of root will produce new shoots. The plant spreads with rhizomes -- long tubular roots -- as well as by seed. So the community went with the use of herbicides.
We started three years ago, and we had 27 acres growing along our shoreline. We really attacked it as a community. We did a lot of education with property owners, we formed a collaborative of property owners, the townships, the DNR and we really went at this.
This is the third year for the herbicides, and a new survey shows that less than half an acre of phragmites remain. And the 50-foot runners that trailed along the beach are gone.
By acting early to control this, it was so much easier than waiting. If you go to Saginaw Bay, which is full of phragmites, theyre spending millions of dollars and using helicopters to apply it. I went to Warpole Island in the mouth of St. Clair River, and its awful. They have acres and acres of it. Its so thick, the turtles cant get on the island. The people on the island cut little paths on the water so the deer can climb ashore between the islands. Its that thick.
Grassmick said they used two herbicides glyphosate and Imazapyralong with a surfactant. However, she did not see any dead fish or amphibians. She frequently walks the shoreline, and saw tadpoles swimming at a former phragmites site, she said.
Anyone tackling this problem should hand-wipe areas in which endangered species are growing, and to be careful not to kill any other vegetation when spraying, she said.
We went to Harsens Island (in Michigan), and theres one man there who believes in arming every property owner with their own spray can. We had individuals who were getting the stuff without a permit, not using the correct chemicals, and not identifying the proper plant, she said. Weve been very cautious it couldnt be applied if the wind conditions are over five mph. There are all sorts of controls built into this.
A U.S. Forest Service report said that phragmites has 26 natural predators, including five native to this country. Scientists at Cornell University are trying to find a biological answer to killing the plant, much like weevils are now being used to control milfoil in inland lakes. But the answer wont come in time for this area, Piccolo said.
Roger Knutson, a Charlevoix resident and retired professor of botany, believes that nature will take its course, although not on a timescale humans prefer.
Already at the township level, theres an urge to have zoning laws, ordinances prohibiting the presence of phragmites in your township, and thats right close to silly, it seems to me. Its a little bit like prohibiting dandelions and just about as effective.
The effect on any other set of organisms will be very, very small. It wont eliminate any other kind of plant. In the whole history of botany, there is no example of a plant from some other place that invaded and eliminated some other plant already there. Its never happened. The world is sufficiently complicated and it pretty well takes care of itself -- just not on a timescale we would like.
Picollo couldnt disagree more.
I did my graduate research in Chicago, where there is horrible phragmites. Youll see huge swamps and lakes that are nothing but phragmites from shore to shore. Its growing, growing, growing, with nothing to keep it in check.
I dont know anyone who says to let nature take its courseto sit back and watch phragmites replace all native vegetation. For me as a wildlife biologist, I wouldnt be doing my job if I let that happen.