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You don't need toxic chemical herbicides to create a beautiful, thriving lawn, garden, or landscape. Before you reach for the Roundup, try these natural methods that are healthier for you and the environment.

How to use natural weed control

Identify the weed

The simple definition of a weed is a plant that's not wanted, or at least not wanted where it's growing. Weeds are plants that are well-suited to the local climate and growing conditions, which makes them prolific and resilient.

How you eliminate or control the weed depends on whether it's an annual, biennial, or perennial. Annual weeds complete their growth in a single season and have shallow roots. Annual weeds should be destroyed before they flower and make seeds. Perennial weeds are harder to remove since they may have large taproots, rhizomes, or stolons (runners) that are hard to get rid of completely. The tiniest piece of root remaining after pulling a perennial weed can produce a new plant.[1]

For help on identifying weeds, see "External Links" below.

How to prevent weeds

The best natural weed control starts with prevention. Try these weed-prevention tips:[2]

  • Disturb the soil as little as possible. Weed seeds can lie dormant in the soil for many years. Cultivating the soil by raking, tilling, or turning it over uncovers these dormant seeds—within days you’ll have weeds appearing. Once on the surface, they receive the water and sunlight they need to make them grow. In the vegetable garden, use no-till growing methods, if possible.[3]
  • Destroy weeds before they flower and go to seed. [4] Once this happens, your problem becomes much worse, especially if these weeds are added to your compost. Compost must be hot (140-160°F) to kill the weed seeds, and most home compost operations don't reach these temperatures.
  • Don’t leave areas of bare soil which invite weeds. Plant flowers and vegetables close together—without overcrowding—to cover open spaces where weeds can take hold. In the vegetable garden, practice interplanting and succession planting to keep beds productive and weed-free.
  • Use crop rotation in the vegetable garden. Some crops provide natural weed control.
  • Apply mulches around plants. Organic mulch one to three inches deep prevents weeds.
  • Plant a cover crop in beds in the vegetable garden that are fallow. Cover crops such as buckwheat or winter rye prevent weed growth—both are allelopathic—they contain natural growth inhibitors which release toxins that suppress the growth of certain weeds.
  • Choose the correct watering system. Use soaker hoses, drip irrigation, watering cans, and container watering systems that only water plants you want to grow, not bare earth between garden rows, for example.

How to get rid of weeds

  • Use a hoe to uproot small, emerging weeds. In the vegetable garden, a stirrup hoe—so named because it looks like the stirrup on a horse’s saddle—is a good weeding implement. Use a back-and-forth motion, which requires minimal effort. A hoe cuts weeds just below the soil’s surface and doesn't disturb the soil enough to bring dormant weed seeds to the surface.[5]
  • Hand pull large, established weeds. Hold the weed by the base of it's stem, and make sure to pull out the whole root.
  • Use a garden trowel to dislodge a deep or stubborn root.

The best times to weed

 

  • Weed prior to planting and when seedlings first come up. If you remove weeds for the first month after seeds emerge, plants will be large enough to compete with weeds that show up later on.
  • Weed often enough to get rid of weeds when they’re small. It’s a lot less work in the long run, and keeps weeds from taking over.
  • Weed with a hoe when the soil is dry. The tiny seedlings will then wither in the sun and can be discarded.[6]
  • Pull large weeds after it rains. Even large tap roots come out more easily when the ground is wet.[4]

Other weeding tips

  • With lawns, use the 10 percent rule. If your lawn is 90 percent grass, and less than 10 percent weeds, it's not worth treating.[7]
  • Discard pulled weeds. Left lying around, they can take root again, especially in wet weather.
  • Don't cultivate too closely to shallow-rooted plants which can damage fragile roots.
  • Don’t mulch with hay or you could make your weed problem even worse.
  • Learn to distinguish weeds from vegetable seedlings. They can look a lot alike—mark your rows and don't weed until you're sure what your seedlings look like!

Why control weeds?

The desire to eliminate weeds in lawns and landscapes is largely driven by aesthetics. In the garden or on the farm, weeds affect crop yields. Weeds compete with lawn, garden, and landscape plants for water, sunlight, and nutrients. They can also invite pests and transmit plant viruses. As they become larger, weeds can shade small seedlings and even crowd out plantings altogether.[8]

Are all weeds bad?

Not all weeds are undesirable. Some—such as wildflowers—are ornamental, while others are edible "wild foods." Many "weeds," including violets, were intentionally introduced to the US as ground covers. Clover was once a highly desirable lawn plant, until the 1950s when a company launched a PR campaign denouncing clover, and then—predictably—introduced an herbicide that killed it.[9]

Although weeds get a bad rap, weeds serve many useful purposes, such as preventing the erosion of bare soil and providing food and a habitat for birds and beneficial insects. If you have the space, it’s a good idea to leave a “wild” spot in your landscape where natural grasses and plants are welcome.[1]

Find it! Natural herbicides and weed fighters

Before you buy

Look for non-selective weed killers made from vinegar and citrus or vinegar and clove oil—or make your own.[10] If you do buy non-organic herbicides, avoid products that contain glyphosates (in broad spectrum herbicides) and 2,4-D (in many "weed-and-feed" lawn products).[11] Find out what the inert ingredients are: while they're not listed on the label, they could be toxic. See "Controversies."

Using natural weed control helps you go green because…

  • It eliminates the need for toxic chemical herbicides (weed killers).
  • It keeps herbicides out of streams, rivers, and other waterways.
  • It eliminates exposure to herbicides which have been shown to cause serious genetic damage and health problems in both people and wildlife.

Two of the most commonly used chemicals in herbicides sold for home lawn and garden use are atrazine and glyphosate. The Union of Concerned Scientists notes that while glyphosate is generally preferred over atrazine, and is considered less toxic, "a switch from one herbicide to another does not result in an environmentally sound agriculture."[12]

Glyphosate, the active ingredient in the well-known weed killer Roundup, is the most widely used pesticide in the US. It is the most commonly used agricultural pesticide, and the second-most commonly used home and garden pesticide. Over 5 million pounds of glyphosates are applied in home settings each year. The US Environmental Protection Agency (EPA) estimates that between 103 and 113 million pounds of glyphosates are used in the US each year.[13]

Glyphosates are broad-spectrum herbicides that are not selective about what types of plants they kill. They are commonly used to control weeds in sidewalks, patios, yards, gardens, roadsides, utility rights-of-way, and along railroad beds.[14]

Studies show that glyphosate herbicides cause genetic damage and immune system damage in fish, and genetic damage and abnormal development in frogs. Glyphosates also increase the severity of a variety of plant diseases.[15]

Monsanto is the leading worldwide supplier of glyphosates. The Roundup family of products and other glyphosate agricultural herbicides produced by Monsanto are not only popular in the US, but are some of the world's most widely used herbicides—registered in over 130 countries and approved for use on over 100 crops. In addition to glyphosates, residential formulations of Roundup may also include other active ingredients to kill weeds faster or to keep them from growing back for a longer period of time.[14]

Glyphosates aren't the only problem. The Environmental Working Group found agricultural weed killers—including atrazine, cyanazine, metolachlor, and acetochlor—in the tap water of 28 of 29 cities tested. In 13 cities, the average level of weed killers in the tap water exceeded federal standards.[16]

The commonly used herbicide atrazine has been shown to cause severe hormonal damage to wildlife, including amphibians, reptiles, and fish. The European Union (EU) banned the herbicide because of safety concerns in October of 2003, while the EPA chose not to restrict the herbicide, despite hundreds of pages of research findings by the EPA's own scientists detailing the environmental and health risks of the chemical.[17]

Related health issues

One study in California found that infants exposed to herbicides before the age of one are 10 times more likely to develop early persistent asthma.[18] In addition to asthma and difficulty breathing, exposure to the herbicide glyphosate can cause a host of other symptoms including nausea, sore throat, headache, eye irritation, burning eyes, blurred vision, skin rashes, burning or itchy skin, lethargy, nose bleeds, and dizziness.[19]

In California, herbicides containing glyphosates were the most commonly reported cause of illness caused by pesticides among landscape maintenance workers, and the third most commonly reported cause of pesticide illness among agricultural workers.[20]

In laboratory studies, glyphosate and glyphosate-containing herbicides resulted in genetic damage in both tests of human cells and tests with laboratory animals. Research shows that farmers and others exposed to glyphosate herbicides have increased risks of the non-Hodgkin’s lymphoma, miscarriages, and attention deficit disorder. Laboratory tests also point to glyphosate herbicides reducing the production of sex hormones.[21]

Controversies

Pesticides are made up of "active" and "inert" ingredients. One problem with federal laws, and consequent safety claims made by pesticide manufacturers, is that only the safety of the "active" ingredients must be disclosed on the product label. Inert ingredients, which comprise the bulk of the product, and may be toxic, are not required to be listed. At the EPA's discretion—and there are few exceptions—the label lists only the "total percentage by weight of all inert ingredients." Surprisingly, the same chemical compound that's an "active" ingredient in one product, may be a "passive" ingredient in another, depending on how the company markets the product, i.e. the stated target of the pesticide.[22]

The New York State Attorney General's office has prosecuted scores of companies who used deceptive advertising claims for pesticides and pest control services. Many lawsuits involved companies misrepresenting the health and environmental safety of their products by using the inert-ingredient loophole. Monsanto, for example, implied that Roundup was not toxic to fish, however the "inert" surfactant (which helps spread the active ingredient of the product over the plant's surface) is "highly toxic" to some fish, according to data Monsanto submitted to EPA. Monsanto was required to stop the deceptive advertising and paid $75,000 in penalties.[23]

Also controversial is the development of genetically-modified, glyphosate-tolerant crops, marketed as Roundup Ready. These GMOs have been developed so that fields can be sprayed with glyphosate herbicides, killing weeds, but not affecting the crop.[24] These transgenic seeds are engineered and patented by Monsanto. The company requires farmers to sign a "technology agreement" that states they are not allowed to save seed to plant the next year, and has brought multiple lawsuits against farmers accused of doing so, going so far as to seize crops. A Canadian farmer was sued by Monsanto for having Roundup Ready canola in his field, even though the crop resulted from cross-pollination with a neighbor's field. Monsanto's Roundup Ready transgenic seed includes soybeans, corn, canola, and cotton. In addition to legal issues, some studies (and farmers) have found that Roundup Ready soybeans yielded less and required more use of herbicides than their conventional counterparts.[25]

Glossary

  • allelochemical: A chemical produced by one plant that is toxic to another plant.
  • crop rotation: The practice of growing different crops in succession on the same land.
  • mulch: A protective covering (as of compost, wood chips, or shredded leaves) spread or left on the ground to reduce evaporation, maintain even soil temperature, prevent erosion, control weeds, enrich the soil, or keep fruit (as strawberries) clean.
  • rhizome: An underground stem from a plant that sends up shoots above ground and roots below; examples are ginger and irises.
  • stolon: A horizontal stem from the base of a plant that produces new plants from buds at its tip or nodes, as in strawberries; also called a "runner."
  • taproot: A long deep root, such as a carrot or the root of a dandelion.

External links

Footnotes

  1. Bradley, Fern Marshall and Courtier, Jane (2006) Vegetable Gardening: From Planting to Picking. Pleasantville, New York: The Reader’s Digest Association, Inc.: 93
  2. Bradley, Fern Marshall and Courtier, Jane (2006) Vegetable Gardening: From Planting to Picking. Pleasantville, New York: The Reader’s Digest Association, Inc.: 94-95
  3. Bradley, Fern Marshall and Courtier, Jane (2006) Vegetable Gardening: From Planting to Picking. Pleasantville, New York: The Reader’s Digest Association, Inc.: 94
  4. Emery, Carla, (1994).The Encyclopedia of Country Living. Seattle: Sasquatch Books: 105
  5. Bradley, Fern Marshall and Courtier, Jane (2006). Pleasantville, New York: The Reader’s Digest Association, Inc.: 95
  6. Bradley, Fern Marshall and Courtier, Jane (2006)Vegetable Gardening: From Planting to Picking. Pleasantville, New York: The Reader’s Digest Association, Inc.: 95
  7. Tukey, Paul (2006) The Organic Lawn Care Manual. North Adams, Massachusetts: Storey Publishing: 171
  8. Bradley, Fern Marshall and Courtier, Jane (2006)Vegetable Gardening: From Planting to Picking. Pleasantville, New York: The Reader’s Digest Association, Inc.: 92
  9. Schultz, Warren (1989). The Chemical-Free Lawn. Emmaus, Pennsylvania: Rodale Press: 112
  10. Tukey, Paul (2006) The Organic Lawn Care Manual. North Adams, Massachusetts: Storey Publishing: 176
  11. Washington Toxics Coalition - What Pesticides Should Consumers Avoid?
  12. Union of Concerned Scientists - Roundup Ready Soybeans
  13. Cox, Carolyn, "Glyphosate Herbicide Fact Sheet," 181Journal of Pesticide Reform,182 Winter 2004, Vol. 24, No. 4
  14. Monsanto - History of Monsanto's Glyphosate Herbicides, June 2005
  15. Cox, Carolyn, "Glyphosate Herbicide Fact Sheet," 183Journal of Pesticide Reform,184 Winter 2004, Vol. 24, No. 4
  16. Environment Working Group - Weed Killers by the Glass
  17. Union of Concerned Scientists - Chemical Industry Pressures EPA to Protect Herbicide, not Wildlife
  18. Our Stolen Future - Early Life Environmental Risk Factors for Asthma: Findings from the Children's Health Study
  19. Cox, Carolyn, "Glyphosate Herbicide Fact Sheet," 185Journal of Pesticide Reform,186 Winter 2004, Vol. 24, No. 4
  20. Cox, Carolyn, "Glyphosate Herbicide Fact Sheet," 187Journal of Pesticide Reform,188 Fall 1998, Vol. 108, No. 3
  21. Cox, Carolyn, "Glyphosate Herbicide Fact Sheet," 189Journal of Pesticide Reform,190 Winter 2004, Vol. 24, No. 4
  22. Office of New York State Attorney General Andrew M. Cuomo - The Secret Ingredient in Pesticides
  23. New York State Attorney General Andrew M. Cuomo - The Secret Ingredient in Pesticides
  24. Cox, Carolyn, "Glyphosate Herbicide Fact Sheet," 191Journal of Pesticide Reform,192 Winter 2004, Vol. 24, No. 4
  25. Schubert, Robert "Monsanto Still Suing Nelsons, Other Growers." Cropchoice News (May 21, 2001)