Dear EarthTalk: Are there any environmentally friendly alternatives to using chemical weed killers like Roundup?
—Walter Wyatt, Concord, NH
The active ingredient in Monsanto’s Roundup, glyphosate, is a known toxin. This is, of course, why it is so successful in eradicating pesky weeds. In fact, glyphosate is the most commonly used pesticide in the United States, and the U.S. Environmental Protection Agency (EPA) estimates that over five million pounds of it are used in American yards and gardens annually.
According to Caroline Cox, staff scientist at the Northwest Coalition for Alternatives to Pesticides (NCAP), gardeners wouldn’t use Roundup if they knew about all of the problems attributed to its use. For instance, ingesting about three-fourths of a cup can be lethal. And symptoms of just casual contact can include eye and skin irritation, lung congestion and erosion of the intestinal tract. Monsanto’s Roundup has also been linked to cancer, miscarriages and genetic damage in humans, so it’s no wonder that NCAP and other organizations are pushing for safer alternatives. Environmentally, the product is thought to be implicated in immune system damage in fish and reproductive disruption in amphibians.
Over a recent eight-year study period in California, glyphosate was the third most frequently reported cause of illness related to agricultural pesticide use. And scientists from the National Cancer Institute and three prominent medical centers have shown the use of glyphosate herbicides by midwestern farmers to be associated with many cases of non-Hodgkin’s lymphoma. Roundup also contains other non-active ingredients, contact with which can cause nausea, diarrhea, chemical pneumonia, laryngitis and severe headaches.
Luckily, reports Cox, “There are effective pesticide-free solutions to the weed problems in our yards and gardens.” For instance, mulches made from wood chips, straw, grass clippings or shredded bark can be used to keep weed seeds from germinating. Quite simply, by keeping light from reaching weeds, a thick mulch layer naturally inhibits the growth of the chlorophyll that is the lifeblood of fast-growing weeds.
Cox also says that maintaining healthy, well-aerated soil is essential to a program of chemical-free weed control, and suggests using organic fertilizer where needed. Longer grass, between two and three inches tall, also helps keep weeds in check without chemicals. When weeds do appear anyway, Cox recommends non-chemical weeding tools such as hoes, string trimmers, weed pullers, flame weeders or radiant heat weeders. Local organic nurseries can help you determine which techniques will work best in your area.
One added benefit of giving up the Roundup habit might be the blossoming of beneficial plants, fungi and creepy crawlies in your yard. Since Roundup is toxic to a wide range of important ecological builders like ladybugs, beetles, earthworms and fungi, going without can help bring these species back to work aerating your soil and keeping virulent pests in check naturally.