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A Vegetable Gardening Guide for the Organic Grower
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GROWING VEGETABLES Getting Started Building the Soil Seed Starting Insects Pests Plant Diseases Care & Maintenance Harvest Time Container Gardening  This site is brought to you by www.PlanetNatural.com |
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Controlling Garden Pests Organically All gardeners know better than other gardeners. - Chinese ProverbThe best part about organic pest control is that it boils down to doing what comes naturally. Instead of spending a lot of time and effort applying chemical pesticides that destroy all insects, find ways to work with Mother Nature in your vegetable garden. This can mean encouraging beneficial insects that dine on garden pests, building the soil to promote healthy plants, and choosing disease resistant crops that are suited to your growing area. After all, long before there were synthetic pesticides, there were gardeners. How did they manage? Here I've listed several of the more infamous garden pests you may encounter along with common-sense solutions for controlling them. This information is based on advice from Rodale's Growing Fruits & Vegetables Organically: Aphids. Tiny (1/16" to 1/8") sucking-insects that can be brown, black, pink, white or green. They transmit many viral diseases and attack most herbs, fruits and vegetables. Their calling cards include: foliage that curls, puckers or yellows; stunted growth; sticky "honeydew," which attracts ants and mold. Get rid of them by; hosing off plants with a strong stream of water, releasing predatory insects, like ladybugs, spraying insecticidal soap and pruning off heavily infested leaves or other plant parts. Cabbage Loopers - Cabbage Worms. Cabbage looper larvae are smooth, green caterpillars with two lengthwise white lines. Imported cabbage worms are velvety green caterpillars. Both worms chew large holes in the leaves of cabbage-family members. Handpick these destructive pests from plants whenever they are discovered and use floating row cover to prevent the adult moths from laying their eggs in your garden. Release trichogramma wasps, a tiny beneficial insect, to destroy eggs before they hatch. Apply Bt-kurstaki while cabbage caterpillars are still small. Colorado Potato Beetles. The adults are yellowish orange, 1/3-inch beetles with black stripes on their wing covers and black spots on their thorax. Their larvae are small, dark orange, hump-backed grubs. Both adults and larvae chew leaves and are the most important pest to potato crops in the United States. To get rid of them using organic control options, shake adults onto a ground cloth in early morning and dump in soapy water. Mulch plants early with straw and cover plants with floating row cover until mid-season. Release two to five spined soldier bugs per square yard of plants to go after the adults and use beneficial nematodes to attack the immature stages. Choose resistant cultivars when possible. Corn Earworms - European Corn Borers. Corn earworms, as adults, are small, tan-colored moths. Larvae are one-inch to two-inch caterpillars of various colors. European corn borers are brown moths as adults and their larvae are small, beige caterpillars that feed on corn silks and burrow into ears. They also may damage other vegetables. Fall and spring tilling will expose the overwintering pupae to wind, weather and predators. Release trichogramma wasps early, when moths are first noticed. Spray Bt-kurstaki or spinosad, a relatively new insecticide, to kill young caterpillars. Repeat applications every 4-5 days until tassels turn brown. Cucumber Beetles. These one-quarter-inch, yellowish beetles have either black spots or lengthwise stripes. Larvae are small, whitish grubs. Adults chew flowers and leaves of squash-family and other plants. Larvae feed on corn or squash-family roots. Both adults and larvae spread the mosaic virus and bacterial wilt. To control, inspect plants frequently and handpick any beetles that are found. Treat soil with beneficial nematodes. Apply floating row cover before beetles appear to prevent transmission of disease. Spray adults with botanical insecticides. Remove garden debris shortly after harvest to reduce overwintering sites. Cutworms. As adults they are brown or gray moths. Their larvae are fat, greasy, gray or dull-brown caterpillars with shiny heads. The caterpillars feed on the stems of many vegetables near the soil line, severing them or completely consuming small seedlings. Use collars made of paper, cardboard (toilet paper tubes work great) or plastic around stems and anchor at half above and half before the soil line. One week before setting out plants, scatter moist wheat bran mixed with Bacillus thuringiensis var. kurstaki (Bt) and molasses over the surface of vegetable beds. Apply beneficial nematodes to the soil. Handpick caterpillars after dark. Also, set transplants out later in the season to avoid damage. Flea Beetles. Found in home gardens early in the growing season, these tiny, dark beetles jump like fleas and chew small holes in the leaves of many crops. Larvae are tiny, white grubs that feed on plant roots. Crops may be stunted or killed. Delay planting to avoid peak populations. You can also cover seedlings with row cover and treat the soil with beneficial nematodes. For severe infestations, spray botanical insecticides (pyrethrin, rotenone) as a last resort. Slugs and Snails. Adults are soft-bodies, wormlike animals. Slugs have no shells while snails have coiled shells. Both leave a trail of mucus when they travel and chew large holes in foliage, stems and bulbs. They feast on any tender plant or shrub and may cause extensive damage to seedlings. To control, use copper flashing as an edge for garden beds. You can also trap them under flowerpots or boards or try shallow pans of beer. Collect and destroy them every morning. To encourage predatory ground and rove beetles, grow clover, sod or use stone mulch along your garden's walkways. Protect seedlings with wide bands of cinders, wood ashes or diatomaceous earth. Spider Mites. Adults are tiny eight-legged mites. Nymphs are similar in appearance, but are smaller than adults. Adults and nymphs suck plant juices from many food crops. Early damage will show as yellow-specked areas on leaf undersides. Adults may spin fine webs. Rinse plants with water and mist daily to suppress reproduction of mites. Release predatory mites, such as Phytoseiulus persimilis or similar species on vegetables. If pest populations are high, use least-toxic, short-lived botanical insecticides (neem oil, pyrethrin, rotenone) to establish control. Squash Bugs. Widely distributed in North America, squash bug adults (5/8 inch long) are brownish-black in color and flat-backed. Nymphs are whitish green or gray when young, darkening as they mature and spider-like in appearance. Both adults and nymphs suck plant juices on all squash crops, which causes leaves and shoots to blacken and die. Hand pick all stages of squash bugs from the underside of leaves. Support vines with trellises to keep them off the ground. Attract native parasitic flies with pollen and nectar producing plants. Cover plants with floating row cover and spray with botanical insecticides if pest levels become intolerable. Tomato Hornworms. One of the most destructive pests of tomato, potato, pepper, eggplant and tobacco plants. Adults are large, gray moths (4-5 inch wingspan). Larvae are green caterpillars (3-4 inches long) with a red or black horn on the tail. They consume entire leaves, small stems, and sometimes chew pieces from fruit. To control, handpick caterpillars from foliage. Attract native parasitic wasps and other beneficial insects to your garden for long-term control (see Attracting Beneficial Insects). Spray Bacillus thuringiensis var. kurstaki (Bt) while caterpillars are still small. Roto-tilling after harvest destroys overwintering pupae in the soil. |
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