All gardeners know better than other gardeners. – Chinese Proverb
The 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?
Tip: Protect your organic vegetable garden with natural pest control products available at www.PlanetNatural.com. This popular gardening store has been around for years, is highly recommended, and offers one of the largest selections available.
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 aphids 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.
Tip: Apply insecticidal soap every 7-10 days when insects are present, or as needed. Made from naturally occurring plant oils and animal fats, it works by penetrating the protective outer covering of soft bodied insect pests – causes dehydration and death within hours! Leaves behind NO chemical residues and can be used inside or out to kill aphids, mealybugs, spider mites, whiteflies and more.
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 potato beetles 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.
A Word About Bacillus thuringiensis (Bt) and GMOs:
Bacillus thuringiensis (Bt) is a natural occurring, soil-borne bacteria that has been used since the 1950s for biological insect control. This bacterium produces a protein crystal that when ingested by the pest causes major damage to the digestive system and leads to death. That toxic protein is unique for each subspecies of Bt therefore yielding a variance of Bt toxic to targeted insect species. The basic mode of action for Bt is that the toxic crystal is activated and released in the insects highly alkaline gut. This changes the osmotic potential and membrane structure of the intestine. Once penetrated by the protein crystal the insect dies by poisoning from its stomach contents. This unique mechanism is what makes Bt harmless to birds, fish and mammals whose acidic gut cannot activate the crystal protein.
Recently, Bt has been questioned for its use as an organic biological insecticide due to its inclusion in Monsanto’s GMO corn and cotton. The differences between the Bt used by organic gardeners (shown at left) and that which is genetically inserted into Monsanto’s crops are dramatic. The naturally occurring Bt toxin is produced and regulated within the bacterium versus modified crops which only contains the gene to synthesize the toxic protein. Bt is quickly degraded when exposed to sunlight so by the time the targeted insects are dead, so is the Bt. In modified crops, the synthesized protein remains protected and active throughout an entire season and without crop rotation resistance occurs. Targeted use of Bt products for insect control on properly managed plots have not resulted in insect resistance. When used appropriately Bt continues to be effective on cabbage worms, tent caterpillars, potato beetles, mosquitoes, black fly, and a variety of other insect pests.
Cucumber Beetles. These one-quarter-inch, yellowish beetles have either black spots or lengthwise stripes. Larvae are small, whitish grubs. Cucumber beetles 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. Cutworm 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) as a last resort.
Slugs and Snails. Adults are soft-bodies, wormlike animals. Slugs have no shells while snails have coiled shells. Both slugs and snails 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.
Tip: Sluggo Organic Slug and Snail Bait contains a unique blend of iron phosphate, an organic compound that breaks down into fertilizer. Controls snails and slugs, yet is non-toxic to wildlife, people and pets. Apply evenly at about 1 lb per 2,000 square feet. Re-apply as bait is consumed. Approved for use in organic gardens.
Spider Mites. Adults are tiny eight-legged mites. Nymphs are similar in appearance, but are smaller than adults. Adults spider mites 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.
Tip: Derived from the seeds and fruit of the neem tree, Organic Neem Oil is a broad spectrum insecticide, fungicide and miticide. Apply indoors or out at 7-10 day intervals to control numerous diseases as well as insects and spider mites on ornamental plants, flowers, vegetables, trees and shrubs. Will not harm beneficial insects such as honey bees and ladybugs. OMRI listed for use in organic crop production.
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. The tomato hornworm 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. Spray Bacillus thuringiensis var. kurstaki (Bt-k) while caterpillars are still small. Roto-tilling after harvest destroys overwintering pupae in the soil.