Monsanto insists Roundup is not carcinogenic, says it has no plans to pull it from the market and is appealing the verdicts. “It’s clear these products are safe when used as directed,” said Rakesh Kilaru, a Washington attorney for Monsanto.
Much of Monsanto’s legal morass stems from a 2015 report from the World Health Organization’s International Agency for Research on Cancer that said Roundup’s active ingredient, glyphosate, was “probably carcinogenic.” More recently, researchers at the University of Washington looked at available data and concluded that Roundup could increase the risk of developing non-Hodgkin’s lymphoma by 41 percent.
Monsanto says the science comes down overwhelmingly on its side. In April, the Environmental Protection Agency reaffirmed its conclusion that glyphosate is not carcinogenic as part of a comprehensive re-registration process of the herbicide. Regulatory agencies in Europe and Canada have reached their own similar determination.
In addition, the long-term Agricultural Health Study of more than 52,000 pesticide applicators, conducted by the National Cancer Institute and others, reported a link between cancers and some pesticides, but not glyphosate.
Roundup has been around since 1974 and historically has been assailed on ecological grounds — that it allows farmers to eradicate the weedy wildflower that monarch butterflies need for reproduction, or that it has been a catalyst for the development of genetically modified “Roundup Ready” commodity crops, with their perceived ills. The vast majority of Roundup sales is to farmers, not homeowners, and it is the world’s most popular herbicide. Monsanto was acquired last year by Bayer AG for $63 billion.
The new controversy about human health may give home gardeners pause. But the question for me is: Does the gardener actually need chemical herbicides? With the exception of the occasional application of crabgrass preventer, I generally don’t use them, preferring to pull or hoe weeds in garden beds and live with them in the lawn. Simply, I don’t want to rely on poisons — this extends to insecticides and fungicides — as a component of my gardening.
This isn’t for the sake of my own health — I have faith in the EPA’s science-driven regulatory system, and when I have used products, I have read the label carefully and followed the instructions diligently. My aversion to them is based on the feeling that pesticides in general aren’t good for beneficial insects, birds and other animals, or for the rich soil biology that is the underpinning of any healthy garden.
If you are turning to herbicides regularly, I think there is something wrong with your approach to gardening.
There are times when herbicides are needed, or at least justified. Some weeds should stay at arm’s length; poison ivy, giant hogweed and the thorny vine named tear-thumb are obvious examples. If you have a large property, say an acre or more, physical removal of weeds can be too onerous. (If you hire a landscape maintenance crew, its approach may be to use herbicides rather than hand-weed. That’s part of the control you lose when others do the work.)
Hardy woody vines may have extensive root systems that cannot be removed without undue effort or machinery. You must cut the stem near the ground and then paint the wound with the applicable herbicide, and such candidates include porcelain berry, English ivy, trumpet creeper, and weedy honeysuckles, bittersweet and wisterias.
Also, the Mid-Atlantic must be one of the weediest places on Earth, thanks to the heat and rainfall of the growing season and the relative mildness of the winter.
So there are reasons to use herbicides. But it’s important to understand that reaching for a herbicide is treating a symptom, not the disease.
Weeds exist in two stages. Where they have overtaken neglected beds and lawns, you must take back the territory. This may involve the use of herbicides, though there are other, non-chemical methods.
After you have beaten back a weed infestation, you have to stop the weeds from returning. Remove them regularly and do so before they set seed.
Avoid the void
Weeds fill empty spaces and germinate in disturbed soil, as buried weed seeds find light and moisture. If you pull or spray a weed without addressing the void, weeds will return swiftly.
The most effective and sustainable remedy for weeds is to crowd them out with desirable plants. In the lawn, this is achieved by having a full, vigorous stand of turf grass. If your grass is receding and patchy, it may be because of an underlying problem such as poor drainage or too much shade. Addressing the cause before you re-seed your lawn will provide greater success for the grass and a better ability to keep future weeds at bay.
In ornamental beds, unplanted areas can be covered in mulch, but it is better (and more satisfying) to smother those areas in plants, in perennial ground covers that will fill in and exclude weeds. Figure out whether your beds are in sun or shade, and plant accordingly.
Organic mulches will suppress weeds, but they often break down into a growing medium where weeds will grow, especially when spread too thickly.
In the vegetable garden, exposed soil is the nature of the beast. When you are growing veggies, and especially as they start out as seedlings, it’s vital to keep weeds at bay by pulling them and carefully cultivating the soil regularly. When beds are not being used, they need to be covered or, better yet, sown with cover crops. This is also true in the colder months as winter annual weeds germinate in October and develop into seeding monsters in March and April.
Winter rye, vetch and clovers, sown now, are green manures that will crowd out winter weeds.
Hoes and other weeding tools
The common or garden hoe is great for breaking up and grading loose soil but not so good for weeding. Some gardeners like an oscillating or stirrup hoe to attack a weedy bed, but I prefer a hoe with a thin, razor-sharp blade for slicing quickly through weeds in tight areas — that is, close to desired plants. The Dutch hoe is such a type, designed to be thrust forward at or just below the soil surface. My choice is a hoe you draw — I use a model with interchangeable heads, using its Interlocken Draw Hoe attachment ($16.99, wolfgarten.us).
The weeding knife doubles as a trowel but is useful for light cultivation of soil and slicing of weeds young and old. One side has a serrated edge. The Japanese version is called hori-hori ($21.99, gemplers.com). I wouldn’t be without it.
For fine weeding — around emerging lettuce seedlings, for example — I use a pocket knife that I keep sharp on a whetstone.
For tap-rooted perennial weeds such as dandelions, use a fish tail weeder to remove the entire plant.
For whole areas being cleared of established weeds, you can use a plastic sheet to trap the sun’s rays and cook the weeds beneath. Solarization works only on sunny sites during the hottest months. Experts say clear plastic is more effective than black sheeting. First, soak the ground. Some solarizers like to elevate the plastic a little — bricks will work — to form an air pocket to cook the weed seeds and seedlings induced into growth by the light, heat and water. The plastic must be secure at the edges against high winds and rips promptly patched.
Sonja Birthisel, a postdoctoral scholar of weed ecology at the University of Maine, says that two weeks should be long enough to kill most annual weeds but that perennial weeds such as yellow nutsedge may take as long as 12 weeks. Caveats: You’re using environmentally unfriendly plastic, it is not instant, and it’s ugly. It can also harm soil microbes, but they will come back, Birthisel said.
Don’t confuse solarization with landscape or weed-blocking fabric, which is typically laid in strips, pinned to the ground and covered in mulch. Shrubs and perennials can be planted through the fabric. I am not a fan of fabric; it prevents you from planting afresh — bulbs, for example — and it invariably becomes visible and looks ugly, among other issues.
If you have large areas of patio, paths or driveways, flame weeders are a way to deal with those pesky weeds that grow up between the cracks and defy hand pulling. Most models are commercial-grade, rely on barbecue-type propane tanks and are pricey. Horticulturist Roger Davis operates one named the Weed Dragon at Longwood Gardens in Kennett Square, Pa.
“It’s perfect for gravel patios, brick paths and patios, slate pavers,” he said. “You would never want to use it in a mulched ring under shrubs or trees.”
Established perennial weeds may come back after a few weeks.
These weeders may be restricted for obvious reasons in areas of the country prone to wild fires. Save the flip-flops for the beach.
“We don’t let just anyone use it,” Davis said. “You have to have a bit of training here on site.”
Vinegar- or acetic acid-based sprays will kill or damage top growth, but formulations that are concentrated enough to be effective herbicides may also be acidic enough to injure the user. They are useful on emerging weed seedlings.
Herbicidal soaps are available and work by using salts to break down the cell walls of targeted plants.
Corn gluten products work as a pre-emergent herbicide; they will kill only weeds beginning to germinate, not established ones. They are expensive, especially if used in quantities required for a lawn, and must be applied at the right time to be effective.
They are sold for use, too, in vegetable gardens, but then you can’t re-seed treated areas for several weeks afterward.
I can’t imagine tying my hands in such a way in the vegetable garden. It’s a place where I’m constantly reworking beds, harvesting, pulling failures and re-seeding.
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