Natural Pest Control for Your Garden
After our recent Facebook post on “green” weed control practices, we received several requests for information about nature-friendly ways to control bugs, fungus, and disease in the garden. Carbaryl, the active ingredient in many chemical-based pesticides, is toxic to humans, very toxic to beneficial insects (bees, lady beetles, parasitic wasps), as well as very toxic to aquatic invertebrates and shell fish. Below are some alternatives you may want to consider. Remember, however, that “green” does not mean “harmless.” Use caution and read the directions on any commercial pest/disease control products carefully.
Fingers: Some pests are easy to spot and can be removed by hand. This is probably the best way to get rids of bugs like caterpillars and the tomato hornworm.
Companion Planting: Several plants have properties that repel harmful insects. French Marigolds (the scented kind) repel whiteflies and kill bad nematodes. Nasturtium has a similar effect and will trap aphids.
Cover Cloth: Particularly useful for protecting your vegetable garden, use row cover (or any cloth that will allow light, water, and air to pass through) to keep insects off your plants. Plants that do not require pollination to produce (such as broccoli and cabbage) can stay covered throughout the season, but others will need to be uncovered when they flower so that the bees and other pollinators can do their job.
Insecticidal Soap: This is a low-toxicity bug control solution that will eliminate small soft bodied insects such as aphids, whiteflies, spider mites and mealybugs. Insecticidal soaps may be used either on indoor houseplants or on outdoor plants, including vegetables. They have several advantages over pesticides in that they leave no nasty residue, are non-toxic to animals and birds, and do not harm beneficial insects. Insecticidal soaps disrupt the cell membranes of the insect, resulting in suffocation. To be most effective, they must be applied vigilantly and thoroughly and may need to be reapplied weekly until you attain the desired result. To make your own, simply mix a few teaspoons of liquid dish soap with one quart of water, then spray or wipe the solution onto the leaves, stems, and buds of the plant.
Neem: Neem oil is a naturally occurring pesticide found in the seed of the neem tree. It reduces insect feeding and acts as a repellent. It also interferes with insect hormone systems, making it harder for insects to grow and lay eggs. Neem is non-toxic to birds and mammals (including humans) and an insect must eat part of a treated plant to be affected, so pollinators such as bees are not harmed by it. It is slightly toxic to fish and aquatic organisms, however, and shouldn’t be used near ponds or streams. Neem can be used as a fungicide too.
Pyrethrins: Pyrethrins are pesticides found naturally in some chrysanthemum flowers. They are a mixture of six chemicals that are toxic to insects. Pyrethrins are commonly used to control mosquitoes, fleas, flies, moths, ants, and many other pests. They excite the nervous system of insects that touch or eat it. This quickly leads to paralysis and ultimately their death. In general, pyrethrins are low in toxicity to people and other mammals. However, if it gets on your skin, it can be irritating. It can also cause tingling or numbness at the site of contact. Dogs fed extremely large doses of pyrethrins have experienced drooling, tremors, uncoordinated movement, and difficulty breathing. Pyrethrins are practically non-toxic to birds but highly toxic to honey bees, fish, lobster, shrimp, oysters, and aquatic insects. This should be your pesticide of last resort!
Sulfur: Sulfur is the oldest recorded fungicide and has been used for more than 2,000 years. It can be a preventive fungicide against powdery mildew, rose black spot, rusts, and other diseases. Sulfur prevents fungal spores from germinating, so it must be applied before the disease develops for effective results. Sulfur can be purchased as a dust, wettable powder, or liquid.
Garlic: While sulfur is a great preventative measure against fungus, garlic can be used after you start to see signs of a fungal infection on your plants. Steep 3 cloves crushed garlic, 1 minced onion, and 1 teaspoon hot pepper flakes in a quart of warm water for an hour, then strain and reserve the liquid. In a spray bottle, mix one part of the garlic-onion-pepper liquid with four parts warm water and add a drop of liquid dish soap. Thoroughly mist any plant showing signs of fungus with the mixture.