According to the Environmental Protection Agency, American agriculture uses toxic pesticides at a rate of more than a billion pounds annually, and only a small percentage of those chemicals actually make contact with a target insect. The remainder is irrelevant to insect control, but constitutes an assault on the rest of our ecosystem. Pesticides suppress the soil food web (the foundation of soil fertility), pollute groundwater and natural water systems, and destroy vital pollinators and other beneficial species.
When a farmer sees a crop being devastated by pests like aphids or mites, it must be tempting indeed to blast them with some toxic chemical and be done with it. But an organic farmer must approach pest control in more subtle ways and from several different angles.
First of all, a vigorous and fast-growing plant can sometimes ward off pests or outgrow their effects on its own. Plants like that come from healthy soil. That is why Nash's Organic Produce works ceaselessly to maintain healthy soil, through the use of cover crops, compost, and crop rotation. Second, we try to time our plantings so that the crops have a head start before the bad bugs hatch and start to eat them. Third, by knowing about the life cycles of insect pests, ways can be found to disrupt their body functions, while doing a minimum of harm to beneficial insects.
The very best way to protect organic crops from insect damage is to break up large fields of row crops with beds of rich, diverse, habitat for beneficial insects. Beneficial insects are predator insects that feed on the pests, like ladybugs, parasitic wasps, lacewings, bees, ground beetles, assassin bugs, spiders, hover flies, and tachinid flies. They like plants with tiny flowers, which have easily-accessible nectar chambers, such as herbs like dill, fennel, chervil, coriander (cilantro), basil and mint; and flowers like asters, marigolds, alyssums, statice, dandelions, buckwheat and the favorite at Nash’s Organic Produce, phacelia.
If you drive by any of Nash’s fields during the growing season, you will see bands of purple phacelia flowers that attract not only predator bugs, but pollinators. Phacelia grows well on the North Olympic Peninsula and when it’s in bloom, it’s humming with all kinds of good insects. They spread out from the flowering beds to feed on the bad bugs in the vegetable beds.
Slugs are generally not such an issue on Nash’s farm. They may chomp a little on the outside edges, but when soil it tilled, they find it hard to move over it. On the occasion when they are a problem, like in a strawberry patch, for instance, the crew has erected temporary fencing and put in a small flock of ducks, who just love to eat slugs!
There are also insecticides extracted from plants or derived from naturally occurring sources that are certified for organic agriculture, but we generally use them as a last resort. Examples of botanical insecticides include neem extract (from a tree in India) and pyrethrum. Materials derived from other acceptable sources include soaps, vegetable and mineral oils, and sulfur dusts. These clog up the insects' breathing organs or disrupt their reproductive cycles. We are careful to apply them as directly and sparingly as we can so as to do as little damage as possible to the beneficial insects.