WHY and HOW We Remove Invasive Plants

by Barbara Walvoord, 8/11/17

WHY Do We Remove Invasive Plants?

Some have argued that invasives do have uses, that they are inevitable, and that we should welcome them or at least allow them to do their thing. Critics sometimes accuse the native restoration community of quixotically trying to restore nature to its pre-colonial state.

Here at Lathrop, we are not naieve. We are not trying to restore Lathrop to the pre-colonial environment, nor are we attacking all plants that arrived after that date.  Rather, we follow these science-based principles (we rely heavily on Douglas Tallamy, Bringing Nature Home, updated and expanded edition, 2007):

  1. Plants are the basis of food chains for most living things, because they turn sunlight, water, soil, and air into food. Creatures, including us, eat the plants directly or eat other creatures that eat the plants.  We destroy these food chains at our peril.
  2. Insects are critical to food chains. Insects are a major eater of plants, and are themselves food for other creatures.  For example, 96% of terrestrial birds need insects, not just nectar and seeds, to raise their young.  90% of plant-eating insect larvae eat plants from only one or a few plant families.  For native insects, there are overwhelmingly native plants with which the insects have co-evolved, so that they have developed the body chemistry and mouth parts to overcome the plant’s defenses against being eaten (Tallamy, pp. 24, 52).
  3. The problem with alien plants is that, when they leave their native land, they leave behind the insects that co-evolved to eat them. Science shows that habitats dominated by native plants support significantly more insect biomass and birds than habitats dominated by alien plants (Tallamy, pp. 63-64).
  4. Alien plants become invasive when they crowd out native plants and form monocultures. Many invasives were imported by people who did not realize that, once escaped from cultivation, these plants would wreak havoc on native ecological systems.
  5. At Lathrop, we remove alien invasive plants from our land, not because we hope to restore a pre-colonial environment, nor because we hate aliens per se, nor because we want to spend a lot of time and money managing the outdoors, but because these alien invasives are a direct threat to our survival and the survival of the birds, bees, butterflies, and other creatures we treasure.
  6. Humankind has managed this land as long as they have lived here. Like it or not, we are part of the natural environment and we greatly influence it.  In the face of the catastrophe of invasive plants, we cannot now abandon our responsibility to manage our land for the greatest benefit of the creatures whose lives depend on it.
  7. We understand that we cannot by ourselves stop the global catastrophe presented by the spread of alien invasives, as well as by climate change, development, and other human practices. But we work locally, on our own land, to slow the catastrophe, to save one tree, one meadow, one bird.  In the same way, we support a local food pantry despite the fact that we cannot eradicate hunger; we establish one clinic even though we cannot provide health care to all those who need it.

HOW Do We Remove Invasive Plants?

Herbicides affect humans, wildlife, and plants. The greatest dangers, rightly targeted by environmentalists, comes from spraying herbicides over a whole area, by air or by tractor. At Lathrop, we use herbicides only when other methods are not possible. We choose the safest possible herbicides. We do not spray areas indiscriminately; we use herbicides to target individual plants.

This list of our methods begins with the least toxic:

  • Hand pulling, mowing, and other mechanical means. We use this whenever possible. Volunteers pull invasives such as garlic mustard, bishop’s weed, and seedlings of shrubs and trees. We also use mowing and weedwhacking.
  • Smothering. We cover small areas with a groundcloth called Lumite, which lets in water but not sunlight, thus killing everything under the cover.  We cut holes for trees and shrubs we want to save.
  • Cut-stump treatment for invasive shrubs, vines, and trees. We cut off the stump near the ground and coat the stump with herbicide, using a sponge applicator called a Buckthorn Blaster, available online. Our contractor, Polatin Ecological Services, uses its own mix of these herbicides, following regulations and permits from the Conservation Commissions of both Easthampton and Northampton.  Our volunteers use either Roundup (Mid-July through February) or Triclopyr (March through mid-July).  It is legal to use these herbicides except within 100 feet of a stream, pond, or wetland (rough estimate of a wetland–look for cattails).  In MA, only certified people are allowed to apply any herbicide or pesticide to wetlands or bodies of water. You can get a sponge applicator already filled with the appropriate herbicide from Barbara Walvoord and Sharon Grace (walvoord@nd.edu or 413-203-5086).

o   Glyphosate (GLY-fo-sate). Available in hardware and garden stores. Look for glyphosate only, not in combination with other herbicides.  Our volunteers use Roundup Super Concentrate, which is 50% glyphosate, and dilute it 1 x 1 with water to get the 25% solution recommended by experts.

o   Triclopyr (TRICK-low-peer).  Our volunteers use Bonide Stump Out Stump and Vine Killer, which is 8.8% triclopoyr as the triethylamine salt.  Purchase it at hardware and garden stores.  It comes with a brush applicator already attached to the bottle cap, but we prefer the Buckthorn Blaster sponge applicator because it takes only one hand to apply, and there is much less chance of spillage.

Our research has shown that these two herbicides are accepted as the least damaging to non-target species and to earth and water. We will continue to research this issue, ask the advice of Polatin Ecological Services, and advise our resident volunteers.

  • Foliar Spray. Our volunteers do not use spray. Or contractor’s workers, who are state certified for herbicide application, use a back-pack sprayer with a wand that has a cone on it to prevent drifting of the spray.  The herbicide is a weak solution (0.1%-2%) of either glyphosate or triclopyr. The spray is applied to one plant at a time, only when the air is calm.  If the plant is tall, it is cut down first, and then, when the new shoots come up, they are sprayed, in order to keep the spray close to the ground, rather than spraying up into the air. The team complies with state and local regulations concerning use of herbicides in jurisdictional wetlands and with the requirements from both towns’ Conservation Commissions, as the Commissions have granted permission for this work.

Nurturing Lathrop’s native plants and wildlife.

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