Organic pest control methods are generally less environmentally damaging and toxic. Whenever possible, you should use the least toxic method first. There are some very effective natural pest control treatments available. The good news is, with the proper preparation and cultural practices, rarely if ever will you need to get beyond the first few levels of defense.
The first step in controlling pest is to create the most hospitable growing environment for your plants. A healthy garden is the single best organic pest control treatment there is. It creates biodiversity. So, without the need to apply any sort of treatment, beneficial insects are doing your pest control for you.
Although beneficial insects are incredibly effective, you’ll likely have to have a bit of tolerance for some pest damage. Organic methods typically are not as fast acting, and yet can be every bit as effective as synthetic controls over time.
With any pest control treatment, the first step is to identify the offending pest, and target a control method that affects just it. You don’t want to apply a non-selective chemical that may kill beneficial insects as well! There are a good number of organic options available, and some are more specific to certain pests than others. Here are some of the more popular options in order of least to most toxic.
These insecticides cause the pest 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 or worm larvae from hornworms to cabbage loopers, and cutworms. The bacteria in Bt paralyzes the digestive system of the larvae, and within a couple of days, the pests are dead. If there is a downside to this type of insecticide, it’s that it is not as fast acting as you might like, but it is very effective and well worth the tradeoff.
These oils work by suffocating the pest. The oil coats them with a petroleum-based liquid, cutting off their oxygen supply. This method of control 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. It contains additional chemicals, which 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.
These soaps utilize the salts and fatty acids within them to target many soft-bodied pests including aphids, whiteflies, mealy bugs, earwigs, thrips, and scales. The insecticidal 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.
These 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 can be toxic to beneficial insects as well, so use them sparingly, as with any pesticide. Insecticidal soaps have not shown to be toxic to humans and other mammals.
Neem is a broad-spectrum insecticide, acting as a poison, repellent, and deterrent to feeding. In addition, it also sterilizes certain insect species, and slows or stops the growth cycle of others. Neem comes from many parts of 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 it’s systemic properties. Plants take up the neem extracts through plant foliage and roots, where it is present in the plant tissue. Consequently, 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. In this way, you will minimize the damage to beneficial insects.