Methods of organic pest and disease control have come a long way from the days when pest control meant reaching for a can of insecticide and zapping the offender. Today many natural, inexpensive methods are available to fight diseases, insect pests, and unwanted intruders in the garden without the use of chemicals or other harmful deterrents.
An Ounce of Prevention
The principles of organic gardening are based on a balanced ecosystem. The two best defenses against pests and disease are to start with healthy soil and healthy plants that are suited to your climate and growing conditions.
Inspect plants and seedlings before you buy them to make sure they’re free of pests and disease. Dispose of diseased garden plants properly? Put them in the trash; don’t add them to the compost pile.
Proper hygiene is also important to prevent disease. Clean and disinfect plant pots and garden tools with hot water and detergent at the end of each gardening season, before putting them away.
Other important preventative measures: appropriate irrigation, choosing disease‐resistant varieties, rotating crops, and proper weeding.
Timing is Everything
Two keys to preventing insects, wildlife, or disease from destroying your crops are timing and vigilance. Check crops every day or two for signs of insects or disease, and act quickly to remedy any problems. Don’t water the garden too late in the day, which encourages fungal disease. Time plantings so that crops won’t mature when their primary insect predators are at their peak.
With companion planting, a plant benefits from close proximity to another type of plant. Advantages include attracting beneficial insects and predators, repelling harmful ones, and aiding growth.
Some vegetable pairings help control insect pests. For example, growing corn, broccoli, or radishes near cucumbers can deter cucumber beetles.
Members of the Allium family, such as onions, garlic, and chives have a strong odor which repels aphids, carrot flies, moles, and weevils. Alliums also help prevent fungal diseases and their flowers attract beneficial insects. Some flowers are great companions in the garden? marigolds, for example. African marigolds give off a powerful ?allelochemical? which repels nematodes. French marigolds attract hoverflies, which eat aphids.
Fences and Barriers
One line of defense is preventing pests or wildlife from access to your crops, using fencing, hedges, netting, or row covers. Fencing may be the only long‐term remedy for a persistent problem with animals such as badgers, rabbits, or deer.
Other barriers such as commercially‐available insect, bird, and animal nettings can also be effective. A thick hedge can discourage deer or other large predators and persuade them to go elsewhere. Even thorny canes, from pruned blackberry bushes for example, can discourage smaller predators. Row covers made from horticultural fleece or cheesecloth can protect crops from flying insects such as aphids, carrot flies, and cabbage flies. It prevents them from landing on plants and laying their eggs. Be aware that pests that do find their way undercover will be protected from their natural predators, however, thus increasing your problem!
For caterpillars, slugs, beetles, and insect larvae, handpicking is a simple solution. Squash the bugs or drop them into a can of soapy water.
Hot pepper spray is an effective repellent for many garden pests including deer, aphids, whiteflies, and many detrimental beetles. Commercial sprays are available, and homemade recipes abound. One easy recipe: Mix 1 teaspoon of dishwashing liquid, 2 tablespoons of any hot red pepper sauce, and one quart of water. Dishwashing liquid helps the spray to adhere to the plant. Reapply after a rainstorm or overhead watering. Be careful not to use when plants are in flower, as the good bugs don’t like hot pepper either, and won’t pollinate your plants!
Attract beneficial animals and birds that feed on pests by providing shelter, water, food, and nesting sites. Toads, frogs, and hedgehogs, for example, all feed on slugs. Add a water feature such as a man‐made garden pond or birdbath to attract birds and other garden‐friendly wildlife.
Pheromone traps, which can control many types of harmful moths and beetles, use synthetic mate‐attracting chemicals to lure harmful insects and trap them, thus controlling the insect population. Beware that they may be too alluring, however, and attract even more of the offending pests to the vicinity!
Other Natural Controls
There are many beneficial predators and parasites that occur naturally in the absence of chemical pesticides (which not only kill the good bugs, but also their food source). Helpful insects include ground beetles, hoverflies, ladybirds, lacewings, beneficial nematodes, parasitic wasps, and predatory midges.
Insecticidal soaps are a good option for a severe insect infestation. Pyrethrum, made from dried flowers, is effective against aphids and flea beetles.
Sprinkle wood ashes, diatomaceous earth or sharp sand around plants to deter cutworms, slugs, and snails; sprinkle wood ash on plants to prevent beetles. Be aware that wood ash raises soil pH, and don’t use wood ash around toads, as it is toxic to them.
These are just a few ideas to keep your garden healthy without resorting to chemical controls. Try a combination of methods and keep track of which ones work best in your garden.