"Chemicals, Chemicals, I Need Chemicals!"

The title for this post comes from George W. Hayduke, the paranoid, redneck eco-warrior character in Edward Abbey's The Monkeywrench Gang.  Hayduke measures highway miles in six-packs - "every freeway a free-for-all"- and the chemicals he craves (coffee, cigarettes and Schlitz) fuel his campaign of sabotage against the rampant development and destruction of the desert southwest.  For Hayduke and an intrepid band of proto-Earth Firsters, the ends justify the means, so turning the tools of modern society against itself while consuming some of its most addictive products is not a contradiction that troubles them terribly much.  The value of the wilderness they are fighting to save is much greater than the minor subsidizing of big tobacco and the like that comes from fueling Hayduke's addictions.

Environmentalists make compromises with modernity.  Even the most self sufficient "back to nature" adherent will favor modern matches over tinder and flint.  The Amish sometimes lease land for cell towers and farm in their shadow without telephones in their houses.  Our tools and taboos reflect our values, an ethical cost/benefit analysis we negotiate throughout our lives.  Sometimes we make different choices and modify our behaviors when presented with new information that casts our customary practices in a negative light.  Recycling is one such example.  The old practice of disposing recyclable waste in landfills has proved economically as well as ethically unsustainable and a combination of incentives and environmental education has modified how we treat our household trash and product packaging.

Even so, there are many environmental dilemmas with imperfect solutions, and whether or not these are adopted depends greatly on what we as individuals and society value.  I was recently asked by friends at Whorled Leaves about the costs and benefits of using herbicide to combat invasive plants, an ethical quandary of the first order.  They, along with many environmentalists and environmental organizations, recognize the significant threat to our landscapes and natural diversity posed by introduced, invasive plants and animals, but are also quite rightly cautious about the impacts of using of chemicals to combat them.  When a globally engaged conservation organization of the size and complexity of The Nature Conservancy tackles invasive species with the full range of tools at its disposal, including, where it deems appropriate, the use of herbicides, it makes these choices based on values that we need to understand in order to either increase our level of comfort with its practices or to better challenge the assumptions that underlie them.

I have considerable experience both with invasive plants and TNC, having been involved as an employee of one with combating the other for seven years.  I used to start my presentations on invasives with a discussion of values.  "Good and bad are not attributes of species", I'd say, "they are value statements we make about their behaviors."  The horticultural industry, which has come a significant way on the issue of invasives in the last decade, emphasizes "the right plant in the right place."  Those plants, animals, and pathogens that evolved elsewhere and can out-compete or even cause the extirpation of naturally occurring species when introduced to new regions can have far reaching impacts on things we value - biodiversity, historic landscapes, outdoor recreation, farms and forestry, to name but a few.  Invasive species are dramatically altering the ecology of habitats both common and rare, and are the second leading cause of biodiversity decline after habitat destruction worldwide.

With impacts like these, it is no wonder that The Nature Conservancy, a biodiversity-driven conservation organization, would prioritize reducing threats to native species posed by invasives.  The ethical as well as practical problem arises when it comes to invasive species prevention and control.  Invasive species are so successful because they have a host of attributes that make them very hard to eradicate once they become established.  There is an exponential and diminishing rate of return on investment in invasive plant control the larger the invaded area and the longer the invasives have been established.  Some invasive plants are so overwhelming that even  when they form a very small percentage of the overall plant diversity in an area, they are poised to dominate native habitats in a very short time.  Garlic Mustard in the Northeast reaches the threshold where it starts to out-compete native plants at less than 2% cover.  Old World climbing fern, spread by airborne spores, has smothered the Everglades and is advancing with astounding speed upstate through Florida's wetlands.

Invasions of these magnitudes can only be addressed at the scale of the threat through management that includes herbicides.  A minor percentage of invasive plants currently in this country has these system altering attributes and the capacity to expand explosively in a few short years.  A decision to manage these species will be based on the values of the individual or entity that contemplates the management.  For The Nature Conservancy, the native diversity it values is directly threatened by invasive species -admittedly some far more so than others- and it has made an accommodation with the selective use of herbicides to manage invasives. 

TNC's Global Invasive Species Initiative, formerly the Wildland Invasive Species Program, provides detailed Element Stewardship Abstracts for invasives and control methods on its website.  The abstract for Phragmities australis, or common reed, describes a host of management options, some more successful than others, including chemical control.  Aerial spraying with Glyphosate, the active ingredient in Roundup and its wetlands approved counterpart, Rodeo, is used on Phragmites where the non-target impacts on native diversity of using a broad spectrum herbicide are minimal.  In sensitive habitats or areas where aerial spraying is either impractical or politically and culturally unfeasible, TNC uses hand application with backpack sprayers, stem swipes or cut stem application directly into the plant using eyedroppers.

Glyphosate has been around for several decades and there has been a good deal of research on its behavior in natural systems and impacts on wildlife and human health.  It bonds with soil on contact, breaking down into naturally occurring compounds including nitrogen and phosphorus.  When applied correctly -targeted application without toxic surfactants in wetlands, on days with low wind, temperatures below 90 degrees and when rain is not expected within 8 hours of treatment, it has few non-target impacts on plants and animals and stays out of the water supply.  It works on some species better than others - you will need something stronger for bittersweet.  TNC has a high level of comfort with its management protocols and with the evidence supporting the use of this herbicide and its known, largely controllable non-target impacts.  That is not to say that people living in communities where TNC uses herbicide feel the same way.  There is far more in the prevailing electronic media stream about concerns with Glyphosate in general than countervailing data about its appropriate use for ecological objectives.

Part of the problem is also an organizational strength of The Nature Conservancy.  Folks who work for TNC really believe in its mission.  A poll taken in 2000 by incoming President Steve McCormick showed that 97% of us fully supported the mission "to preserve the plants, animals and natural communities that represent the diversity of life on Earth by protecting the lands and waters they need to survive."  With that kind of mission buy-in, decisions made by TNC favor doing what is consistent with its values.  It tries to be science-based, pragmatic, and non-confrontational in its approach, but the issue of herbicide use is controversial and it sometimes surprises TNC employees to find that others -even environmentalists- who do not have the same mission add up the ethical question differently.

Another problem is that once you accept that invasive species are a real threat to what you value, and especially if you have struggled with little to show for it using manual or mechanical control methods, you make accommodations with the tools that offer better hope of gaining ground.   You drop a blanket policy against biological introductions to control invasives and develop a protocol for assessing whether and how to use this strategy.  You evaluate the available data on chemical control techniques based on effectiveness and non-target impacts and try and use what will get the job done without unacceptable impacts.  In some communities where I have worked, there is such opposition to herbicide use that it defies logical argument and is driven by pure, values-based emotion.  I made the decision not to spray barberry in one community in the Berkshires, even though I had permits to control it over 2,000 acres of state land using a Congressional earmark, because it cost us too much in community goodwill and in my estimation compromised our ability to do further conservation work there.  It helped that as I weighed the costs and benefits of controlling barberry in that community, I believed that we could still meet our management goals by working in other communities that shared that large forest system and that barberry did not pose the same sort of threat this far into its invasion that other rapidly expanding plant invaders might have.

Whenever one is contemplating land management of any kind, the first and most important question to answer is what are you managing for.  Management that is just about killing weeds is unsound. The desired outcome should be a healthier natural system, an unobstructed waterbody, a healthy rare species population, a regenerating forest.  Invasives may impact all of these objectives, but rarely as the only causal factor and the solution is usually not eradication.  If loosestrife is shading out bog turtle basking habitat and that is what you are managing for, cutting the stems at less than 1' high is a more practical and ethically appropriate solution than using herbicide or pulling up the loosestrife.  The natural community may be degraded but can still be managed for its value as bog turtle habitat.  Some land managers, in their zeal to address a known threat, overlook this primary rule of land management and too readily assume that herbicide use is the most practical and appropriate solution to a problem they may not have fully analyzed.

Where do I fall out in this values based discussion?   I manage for clear outcomes.  I strongly advocate invasive species prevention before they become established.  Because I manage a very small piece of property where I live, I can accomplish most of the invasive control I require through mechanical means.  I use Roundup as a cut stem application on buckthorn and winged euonymus, both of which have extensive root systems that stay green and, in the case of buckthorn, resprout vigorously.  I hand pull garlic mustard and will be doing so for at least 5 years because its seed bank is prolific and remains viable for at least that long.  If I were managing a larger property, I'd consider spraying garlic mustard.  Now that I no longer work for TNC, I am even more convinced that while controlling some invasions at large scales with herbicide is possible, those places where we make that investment and accommodation with chemicals need to be broadly vetted and among the most significant and irreplaceable of our natural resources. 

Sometimes one lives with Loosestrife.

Comments

[lene]

That's really interesting stuff, especially the transpiration of glyphosate, which makes perfect sense. I don't know the details of the knotweed control issue--thanks for giving me a better context to understanding their decision. Do you know if they have looked into mycellium based herbicides? There is a product being studied here in Vermont for ROW's that might be applicable if it continues to be produced. It's also painted on, usually to cut stumps, as a glyphosate substitute. The company previously producing it has since filed for bankruptcy.

PS. By the way, Green Mountain College is offering a new program--MS in Environmental Studies. The program sounds great. If you know anyone interested, you might pass this link along. It's a limited residency program designed for professionals.

http://www.greenmtn.edu/graduate_studies/ms_es/

[Tim Abbott]

Lene, from a purely biological perspective, Japanese knotweed (Polygonum cuspidatum) is very difficult to control. It is rhizominous and can reproduce vegetatively. It is virtually impossible to pull up every fragment of the plant by hand or mechanically. I have tried smothering it in dense layers of black plastic, and found living knotweed persists even two years later. It is particularly aggressive in riparian areas, banks and river corridors, and mats of uprooted knotweed can float downstream in floods and reestablish with ease.

It has a hollow stem like Phragmites, and therefore TNC has applied what it has learned about controlling that plant species with cut stem application of Rodeo to controlling knotweed. My old TNC program, the Berkshire Taconic Landscape Program, pioneered this method at Kampoosa Bog in Stockbridge MA where there is a highly sensitive habitat and many rare species. Because the Phragmites stem draws the herbicide down to the Rhizome, the clip and drip method is the least objectionable from a non-target impact perspective.

There are some drawbacks to hollow stem application. Herbicide can sit in a well above the node for a while before being drawn down by the vascular system of the plant and if it rains a few hours after treatment, the herbicide can leak out of the cut stem. One very hot days with high humidity, Phragmites Rhizomes appear to release Glyphosate after treatment. TNC has documented cattail die-back within a foot or so of the stem on such occassions and other researchers confirm this observation.

Knotweed has a much wider stem than Phragmites, and TNC's own Element Stewardship Abstract for this species says the following about Glyphostate and herbicide application protocols:

"A number of biocidal chemicals have been found to be effective against Polygonum cuspidatum. Most of these are undesirable for use in conservation areas because they are nonselective, may be persistent in the soil and/or are not safe for use near water. One frequently used way to minimize the effects of non-selective herbicides on non-target species is to paint herbicides directly onto the target plants (Broaddus, pers. comm.). In the case of P. cuspidatum, this would probably require prior cutting for easier access if herbicides are to be applied after the plants have reached their full height. Herbicides appear to be more effective when combined with cutting (Scott and Mars, 1984; Orchowski, 1991).

Glyphosate [N-(phophonomethyl)glycine] has been found to be very effective against Polygonum cuspidatum (Ahrens, 1975; Beerling, 1990; Pauly, 1986). Glyphosate is a nonselective systemic herbicide with a short residual life (Ahrens, 1975; Lynn, Rogers and Graham,1979). Application is more effective in the fall when leaves are translocating to rhizomes (Lynn, et al, 1979). The British Nature Conservancy Council (1989) recommends applying 2.0 kg/ha in August with a prior cut in late spring or early summer. Glyphosate is available from Monsanto under the trade names RoundupTM and RodeoTM. Only Rodeo has been approved for use near water (Bender, 1988). Glyphosate has been used with limited success on some nature reserves in the U.K. (Palmer, 1990). Repeated applications over several years may be necessary (Beerling, 1990; Palmer, 1990; Pauly, 1986)."

Cut stem application requires a higher concentration of Glyphostate than foliar spray. TNC uses a 25% solution of Glyphostate for its Phragmites control at Kampoosa. It is labor intensive, and often volunteers precede a licensed herbicide apoplicator to cut the stem and remove the upper portion of the plant for composting offsite.

My question to TNC is what specifically are the unacceptible impacts on biodiversity of the knotweed at the sites where it has decided to control this species. I would hope TNC would not choose to manage this plant simple because it is invasive, but rather because it directly threatened the viability of a particularly rare or irreplaceable species or an outstanding example of a more common natural community type.

I have seen it at its worst on the scoured gravel banks and low islands of major rivers where it dominates these naturally disturbed habitats, and along embankments. Presumeably there are some natural communities and rare species which might be threatened by Knotweed at certain sites, but it is not, at least as far as I am aware, capable of overwhelming vast areas the way that Phragmites and Loosestrife can.

[lene]

Tim,
Thank you for taking time to explicate the theory concerning herbicide use and invasives. Japanese knotweed is a major plant of concern up here, and I've heard that TNC is using stem injections rather than broadcast spraying even though it requires several times more active ingredient per sector of land and has proven to be less effective at controlling the plant. Do you know why they might be choosing to use stem injection versus spraying?