Organic Pest Control Strategies for the Garden

Keep pests in their place with these safe products and organic pest control techniques.


| February/March 2006



American Toad

An American toad eyes a potato beetle.


PHOTO: DWIGHT KUHN

According to an ancient Chinese proverb, “If you would be happy all your life, plant a garden.” Modern gardeners know this to be true, but unfortunately our gardens also seem to inspire delight in grasshoppers, squash bugs and countless other hungry insects. There’s at least one serious insect enemy for every crop, so knowing how to prevent and treat pest problems is fundamental to maximizing the rewards you can reap from your gardening efforts.

When faced with a pest problem, gardeners — new ones in particular — often reach for a solution that comes in a spray bottle. It’s true that many poisons sold in garden centers will kill any, and often all, insects in your garden. (Some of these products are less toxic than others, see Top Organic Pest Control Products for options approved for organic growers.) But spraying chemicals is rarely the best option for getting rid of pests. Many pesticides are hazardous to humans and wildlife, and most will kill beneficial insects right along with the pests you’re targeting.

Organic Pest Control Strategies

Before you march into your garden armed for an insect Armageddon, answer these three important questions:

  1. Are there natural predators capable of controlling this pest? In many cases the answer is yes, but you will never see your garden’s homeland defenses in action unless you actively encourage beneficial insects (see Image Gallery) and adopt a wait-and-see attitude when new pest problems arise. Always watch what happens for at least five days after you see a pest become active. This can be a wonderfully fascinating show. To encourage natural predators, provide food and habitat — for more information, see Protect Your Garden with Beneficial Bugs.
  2. Can you control this pest by using preventive methods? You can prevent attacks from many nonflying insects — as well as diseases — by rotating your crops (not planting them in the same place more than once every three years); by cleaning up and composting dead plants; by eliminating habitats such as weedy host plants; or by growing resistant varieties. Learning to use methods that prevent pest problems does not happen overnight, and even the most experienced organic gardeners pick up new strategies with each passing season. When it comes to learning what works and what doesn’t, your garden often is your best teacher. The books and Web sites listed under “Sources” later in this article also provide excellent advice.
  3. Are there easy ways to capture the pest or to install barriers that will protect the plants? Some insects are easy to pick off and drown in a pail of soapy water, or perhaps you can nab them with pieces of duct tape or a rechargeable vacuum. If you see a certain pest returning to your garden year after year, you often can keep the hordes at bay by covering plants with lightweight floating row covers.

All of the possible answers to these three questions are called cultural controls, which can be remarkably effective. When Cornell University brought together five horticulture experts to summarize the effectiveness of organic pest-control options for 36 vegetable insect pests and diseases, they found that 20 often could be handled using cultural controls. In your garden, the ratio between problem pests and cultural solutions can get tighter as you learn to make use of practical preventive measures.

Know Thy Enemies: Identify Common Garden Pests

It’s important to understand that most garden pests are only capable of damaging a very narrow range of closely related plants. For example, little black flea beetles may make holes in potato leaves in spring, then hop to tomatoes or eggplant in summer, but they won’t veer far from plants that are members of the nightshade family. In similar fashion, the squash bugs that invade your pumpkin patch cannot digest juices sucked from lettuce or broccoli. A few pests do have broad feeding ranges (Japanese beetles eat the leaves and flowers of more than 200 plants, and some grasshopper species have equally varied tastes), but for the most part, garden pests require the presence of specific host plants — that’s where you can target your efforts.

It’s wise to learn as much as you can about the life cycles and physiques of the pests that are damaging plants in your garden. Invest in a hand-held magnifying glass and a good insect identification book, such as Garden Insects of North America: The Ultimate Guide by Whitney Cranshaw. Also bookmark useful online resources. Two excellent places to start are Cornell University’s Resource Guide for Organic Insect and Disease Management and the University of California’s Integrated Pest Management Program.





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