Go with Natural Pest Controls First
Organic pest control methods are generally less environmentally damaging, and less toxic to non-targeted insects, mammals and aquatic life. Unfortunately, in our time-starved world, many people simply want the most potent, one application product—no matter what the consequences.
Pest control strategies in the eco-friendly garden seek to use the least toxic method first. There are some very effective natural control treatments available. The good news is, with the proper preparation, and cultural practices, rarely if ever will you need to get beyond these measures.
The first step in controlling pests, before even applying the most benign treatment is to create the most hospitable growing environment for your plants. A healthy garden is the single best natural pest control there is. Healthy plants are less attractive to pests in the first place, and when they are attacked, the plants are better equipped to defend themselves and recover.
An advantage to the “no-spray” method of control is that beneficial insects have the best opportunity to establish populations in your garden and do the work for you. You may need to exercise a little patience and put up with some cosmetic damage initially. But, they are incredibly effective at natural pest control.
With any pest control treatment, the first step should be to identify the offending pest, and target a control method that only affects that pest. Don’t apply a non-selective chemical that kills beneficial insects as well! There are a good number of organic options available, and some are more specific to certain pests than others.
If there’s a downside to natural pest control methods, most people would say they are not as fast acting, and yet can be every bit as effective as synthetic controls over time. To me, that’s an acceptable tradeoff! Although there are many, here are some of the most common options:
These insecticides cause pests to get sick, are very specific to the target pest, and do not harm beneficial insects, nor are they toxic to mammals. One of the most popular choices is Bt (Bacillus thuringiensis). I use this whenever necessary to treat a number of worm larvae from hornworms to cabbage loopers, and cutworms. The bacteria in Bt paralyzes the digestive system of the larvae. They stop eating and within a couple of days, the pests are dead.
These soaps utilize the salts and fatty acids within them to target many soft-bodied pests including aphids, whiteflies, mealy bugs, earwigs, thrips, and the early stages of scale. The soaps penetrate the soft outer shell of these and other pest, causing damage to the cell membranes. They then begin to breakdown, resulting ultimately in dehydration, and starvation.
Insecticidal soaps can be phytotoxic to certain plants, so be sure to test a small area, before applying on a larger scale. The other downside is that soaps are non-selective so they can be toxic to beneficial insects as well. Use them sparingly, as with any pesticide. Insecticidal soaps have not shown to be toxic to humans and other mammals.
You can make your own by adding a teaspoon of dish soap (not detergent) and a teaspoon of cooking oil to a one quart spray bottle. Insecticidal soaps are also readily available for purchase at nurseries or in garden centers.
These oils work by suffocating the pest. The oil coats them with a petroleum-based, horticultural grade liquid, cutting off their oxygen supply. This control method has been around for a long time. It is primarily used to kill the eggs and immature stages of insects. These products are very effective because they spread so well, and break down quickly. However, these oils can and do affect beneficial insects, but are less toxic to them.
Oils are often used to control aphids, scales, spider mites, mealy bugs, psylla, and some other insects. These oils can harm your plants and trees; primarily leaf damage, so be sure to read the directions that come with the packaging.
Never spray these oils on a hot day, usually over 85 degrees, and its best to spray a small area of your plants first. After a few days, look for any damage from the oil, before commencing with a larger application. If no damage is observed then continue spraying, coating the top and bottom of all leaf surfaces.
This product is the fossilized silica shells of algae. Although these shells are microscopic in size, they’re covered with sharp projections that cut and penetrate the cuticle of an insect. This causes the pest to leak vital body fluids. The result is dehydration and death. The unique aspect of diatomaceous earth is that it is not a poison that causes the damage, but the physical abrasiveness of the dust.
DE is effective against soft-bodied pests including aphids, trips, whiteflies, caterpillars, root maggots, slugs, and snails. However, DE is non-selective, and will potentially kill beneficial insects as well.
Apply DE to the soil for ground dwelling pests, and to the foliage for other pests. DE adheres best to moist foliage, so application is best early in the morning, when leaves are wet from dew, or after a rain. Be sure to use “natural-grade” vs. “pool-grade” DE which contains additional chemicals that can be harmful to humans and mammals if inhaled. In either case, it’s a good idea to wear a dust mask whenever working with any dusting agent.
Neem is a broad-spectrum insecticide, acting as a poison, repellent, and deterrent to feeding. It also sterilizes certain insect species, and slows or stops the growth cycle of others. Neem oil is derived from the Neem tree, which is native to India. Neem is applied as a foliar spray, or soil drench. It is used to kill a wide range of pests, including aphids, thrips, loopers, whiteflies, and mealy bugs.
One unique aspect to this biological agent is its systemic properties. Plants take up the Neem extracts through plant foliage and roots, where it is present in the plant tissue. As a result, Neem is also effective against leaf minors, which are usually not affected by other non-systemic foliar sprays.
Generally, Neem must be ingested to be toxic, and is nearly nontoxic to mammals. Although it breaks down quickly, you should spray Neem only when necessary, and only on plants known to be affected by the pest you are targeting. In this way, you will minimize the damage to beneficial insects.
Botanical Insecticides: Pyrethrin
There are a number of botanical insecticides but we’ll focus on the most popular; pyrethrin. It is the active ingredient extracted from the Pyrethrum daisy. Products containing pyrethrin contain compounds that kill on contact. They are considered broad-spectrum (non-selective) and are used to control many chewing and sucking insects. Do not confuse pyrethrin with the synthetic version called Pyrethroid. It is even more toxic to all insects.
Use caution when using pyrethrin products as they are toxic to fish and moderately toxic to mammals. They are non-selective and harmful to some beneficials including lady beetles. Insecticides using pyrethrum are of particular concern for mosquito control. Although it is marketed as an organic method of dealing with the problem, the mist used to kill the mosquitos is also lethal to many other insects, including honeybees and other beneficials.