Unless you have been living on Mars, you have probably seen the TV ads from law firms seeking cancer patients who have used the ubiquitous herbicide brand Roundup.
Three recent high-profile cases in California have brought verdicts against Roundup’s maker, Monsanto, one with a jury award of $2 billion, later reduced to $86.7 million. To date, more than 18,000 plaintiffs are suing Monsanto in state and federal courts alleging Roundup-related cancers.
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, D.C., 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.
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.
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.
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.
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, nonchemical 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.
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.
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).
Johnny’s Selected Seeds sells a range of sharp-edged hoes. Various Japanese-made hoes have high-quality stainless steel blades and seem readily available online.
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.
Solarization:
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. 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.
Organic herbicides:
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.
