If you ever turn over a bottle of Roundup, one of the most popular chemical weed killers in the world, you’ll see glyphosate listed as the active ingredient. What you won’t see is a list of inactive ingredients. And that’s problematic. Because researchers who recently tested the product’s active ingredient in combination with certain inert ones found the combo makes this weed killer much more toxic than previously disclosed. “It’s not as benign as people are led to believe,” says Greg Bowman, editor of the Rodale Institute’s New Farm online publication, which focuses on nontoxic farming methods. And even the listed ingredient may be more dangerous than was previously thought. “More and more studies by medical and agricultural specialists are revealing the subtle, low-level impact that Roundup’s main ingredient, glyphosate, has on wildlife, soil life, and—directly and indirectly—people themselves,” Bowman says.
THE DETAILS: Researchers tested four combinations of Roundup on cultured human cells, and found that one inert ingredient in particular, polyethoxylated tallowamine, or POEA, significantly boosted the toxic effects of the main ingredient, glyphosate. In the study, the combination of the two killed or damaged many more of the cells than glyphosate alone. The study was published in the journal Chemical Research in Toxicology.
WHAT IT MEANS: In the U.S. alone, farmers and homeowners use an estimated 100 million pounds of the Roundup herbicide a year. The problem is, weeds are becoming resistant to the chemical, so farmers are forced to apply more and more of it. Between 1994 and 2005, the use of glyphosate increased 1,500 percent. And while the manufacturer and the U.S. Environmental Protection Agency say the product is safe, a growing body of nonindustry-funded scientific research suggests otherwise. When the active ingredient alone is tested—which is standard procedure in toxicology testing—the product may seem relatively safe. But when all the chemicals in the product are tested together, which provides a realistic snapshot of the product’s safety, the results suggest much more toxicity.
A recent Rodale Institute article on pesticides like Roundup highlighted some of the research showing the detrimental effects this type of weed killer has on people and amphibians:
• In May 2009, a group of environmental lawyers in Argentina filed a petition to ban glyphosate after a study linked it to embryonic mutations affecting the nervous system and skeletal development in amphibians.
• Government-funded research out of Argentina also found higher-than-normal rates of birth defects and cancer rates in people in areas with glyphosate fumigation.
• In 2005, a study published in Environmental Health Perspectives found Roundup to be toxic to placental cells at concentrations lower than that used in agriculture.
You don’t need nasty chemicals to keep your lawn and garden looking gorgeous—try these techniques and keep dangerous chemicals away.
• Go natural and save money. Protect your family and the environment (and save money in the process) by using tried and true organic techniques from OrganicGardening.com. Hint: Corn meal gluten could be your new secret weapon.
• Get off the Roundup treadmill. A product that becomes less and less effective, forcing consumers to buy more and more of it, may be profitable for the manufacturers. But it’s not so great for your budget. The nonprofit Rodale Institute, a pioneer organization in organic farming, recently investigated the topic of superweeds , ones that have grown resistant to glyphosate-based herbicides like Roundup. The U.S. Department of Agriculture–named “worst weed in the world,” Johnsongrass, is among them. Switch to chemical-free methods for a better bargain.
Tackle weeds with persistence and the right tools.
A thick layer of mulch keeps light from reaching weeds. "Without adequate light, the plants don't produce enough chlorophyll to enable further growth. Most of these plants sicken and die before you even notice them," writes Miranda Smith in Rodale's Chemical Free Yard & Garden. "The few plants that do manage to stick their leaves into the light will be shallowly rooted and very easy to pull."
Organic mulches—straw, grass clippings, leaves, shreddedbark—nourish the soil as they decompose. They are fairly effective weed barriers. For even better weed protection, use several sheets of newspaper, kraft paper (the paper used to make grocery bags) or cardboard under these mulches. In a 1992-93 study at the University of Vermont, a 6-inch layer of shredded newspaper applied at the beginning of one season allowed no more than 8 weeds per square yard to sprout for two summers. Without renewing the mulch layer, the newspaper controlled weeds for two seasons. Kraft paper and cardboard allow even less light to reach weeds and are even more impenetrable.
Annual weeds die when you sever the stems from the roots just below the soil surface. With a sharp hoe, you cut the weeds easily. Forget about the square-headed traditional garden hoe for this job—go for an oscillating or a swan neck hoe instead.
To hoe your garden without cultivating a backache, hold the hoe as you would a broom—that is, with your thumbs pointing up. Skim the sharp sides of the hoe blade through the top inch of the soil.
You can let the sun help you get rid of persistent weeds, if you're willing to leave the bed fallow for six weeks in the summer. Get started in late spring or early summer by pulling, hoeing or raking out as many weeds as you can from the garden bed. Then, moisten the soil and cover it with clear plastic, weighting or burying the edges. Leave the plastic in place for 6 weeks. When you remove the plastic, the sun will have cooked weeds that would otherwise have sprouted.
Corn Gluten Meal
You can suppress the growth of weed seeds early in the season by spreading corn gluten meal over the area where they're growing. Corn gluten meal, a by-product of corn processing that's often used to feed livestock, inhibits the germination of seeds— bear in mind, once the weeds have gone beyond the sprout stage, corn gluten will not affect them. Also, corn gluten doesn't discriminate between seeds you want to sprout and those you don't want, so avoid using corn gluten meal where and when you've sown seeds. It works best in established lawns and perennial beds.
Here's the trick to comfortable, quick weed-pulling:
Put your hands in front of you, thumbs up and palms facing your body, one hand in front of the other. Now roll your hands, like kids do when singing "This old man goes rolling home."
Pinch your forefinger and thumb together as you reach the outermost edge of the imaginary circle your hands are tracing and move your arms to the side as you roll your hands.
With practice, you will be surprised by how quickly you clean up a row in the garden with this movement.
This is your most important long-range weapon against weeds. Mulch well, pull what you can, hoe where you have to and use a handy tool or two for a few minutes whenever you visit your garden. Do these things consistently for a few seasons, and you will slowly, but surely expel the invaders for good.