Dear EarthTalk: What green-friendly lawn and garden pesticides are available today? I’m particularly interested in options that won’t harm my cats. -- Nancy Blanchard, via e-mail
Pesticides have greatly boosted agricultural yields over the last half century, so it is no wonder, given the commercial availability of many of these synthetic chemicals, that American homeowners apply 100 million pounds of the stuff each year to make their own gardens grow bigger and faster, too.
But the downside of using such chemicals is that they can poison people and pets as well as backyard wildlife: “Common insecticide ingredients such as 2,4-dichlorophenoxyacetic acid (2,4-D), atrazine and dicamba have been shown to harm mouse embryos at times equivalent to the first week after conception in humans,” says Erica Glasener of The Green Guide. Due to such revelations, home gardeners are fast discovering the benefits of avoiding chemicals in favor of natural, less toxic alternatives.
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But before thinking about applying pesticides, gardeners can design (or re-design) their gardens to make the most of native plants that have evolved over eons to thrive in local conditions without synthetic aid or lots of water. Choosing native plants appropriate to your elevation, soil type, drainage and sun exposure will naturally repel many common pests and also reduce the propagation of invasive exotic species.
Similarly, embedding your plants in healthy soil replete with beneficial insects and worms can also help reduce the need for pesticides. Laura Moran of Mainstreet.com suggests that home gardeners compost their vegetable food waste—which is chock full of nutrients that plants love—and mix it into existing soil to give the garden a healthy boost. “Aside from stimulating healthy root development,” she writes, “the addition of rich compost also improves soil texture, aeration and water retention.” It also provides a nice home, she says, for the beneficial bugs that are destroyed along with the bad ones by chemical pesticides.
If pesticides are necessary, there are a handful of organic varieties available. Bacillus thuringiensis (“Bt”) is a naturally occurring bacterium that is lethal to most leaf-eating caterpillars on trees, shrubs, flowers and vegetables. According to gardening writer Jeff Ball, it is harmless to all other insects, animals and humans. It comes in a powder form for use as a dust, or, when diluted with water, as a spray. Organic chemists have formulated varieties of Bt to kill mosquitoes or potato beetles as well.
To control slugs in an environmentally friendly manner, The Green Guide’s Glasener suggests recycling the black cell packs that vegetables and annuals are sold in, and placing them (empty) upside down near the base of plants. “Each morning, check the containers for pests, and if you find any, simply throw the container away with the pests inside,” she says. Another easy slug control method is to use hollowed out grapefruit rinds in a similar manner around the base of plants, disposing of them if they turn up any slugs.
Pet owners may already be familiar with insecticidal soaps used to control fleas. Some of these soaps can also be used in the garden to repel insects. For more information, consult a local nursery specializing in organic methods and native plants. Find one near you via the free online Native Plants Nursery Directory.
CONTACTS: The Green Guide, www.thegreenguide.com; MainStreet.com, www.mainstreet.com; Native Plants Nursery Directory, www.plantnative.org/national_nursery_dir_main.htm.
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