Margaret Lauterbach

Your soil and its vital microherd deserve better than sprays full of toxic chemicals

Many of you are new gardeners, whether you’ve just retired and now have leisure to garden or are youngsters just getting into growing food or flowers. Gardening is a lifelong learning process for all of us. We become more keenly aware of the weather, wind and temperature forecasts, as well as the condition of our soil and water, diseases spreading in this valley and insects, destructive or beneficial.

Many new gardeners online betray what they’ve heard about gardening: spraying.

Before you think of spraying anything, consider that the health of your soil is dependent upon the millions of living creatures that are feeding your plants and protecting them from diseases. They’re essentially “translating” the fertilizer we put down so that plants can actually use it to grow and thrive. These microscopic creatures are especially vulnerable to many toxic sprays that gardeners have access to, and when they’re destroyed, our soils are far poorer. The continued existence and good health of this microherd is one of the reasons for organic gardening and should be a caution for nonorganic gardeners.

Nonorganic mulches and many chemicals (fertilizers, or intended controls for disease or insects) harm or destroy this microherd in your soil. The estimate is that a handful of soil contains more microorganisms than there are humans on this planet. Destroying all or part of them destroys the texture of your soil, and destroys its ability to retain nutrients and moisture, as well as the capability of hosting and growing green plants that feed your body or your soul.

How does a gardener cope? By learning and understanding what is happening in their garden, and if necessary, by controlling destructive elements without resort to poisons. IPM (Integrated Pest Management) is a four-step approach that many gardeners now embrace, and all gardeners should. Ask yourself:

1) How destructive is this insect or disease? Will it cause irreparable harm or loss of harvest? If not, do nothing. One insect, for instance, is not cause for concern. I have ants in my garden, and they have done no harm, so I let them be.

2) If damage is intolerably harmful, learn exactly the identification of the disease or creature causing harm.

3) Once you know what the problem is, can you prevent this disease or destructive creature from spreading? If tomato plants have early or late blight, either install mulch or remove lower branches to reduce chances of fungal spores being splashed onto foliage, spreading the disease.

4) If you can’t prevent it, learn the least toxic way to control the disease or harmful creature.

If your problem is an insect, learn what insect it is. Many insects are very specific about what they eat. A squash bug loves some varieties more than others, for instance, and will reluctantly invade other vining plants such as cucumbers, but don’t feed on beans, lettuce, etc. They aren’t as aggressive toward zucchini, climbing zucchini or butternut squash, for example, as they are for most other varieties. I found one squash bug on a bean plant, doing no damage and laying no eggs. That’s just where it landed before I saw it. I knew it would find squash plants and cause damage, so I smashed it between my fingers.

Destructive creatures may be controlled by repellents, diversion to other plants, or killed. Predator urine (available online) works for some vertebrate pests. Strongly odoriferous herbs might conceal plants attractive to some creatures, even deer. Some commercial repellents work for a time, at least. Annoying insects such as mosquitoes may be repelled by thoroughly spraying your yard with a garlic repellent, I’m told.

Stone fruit trees are relatively short-lived because of the invasions of peach tree borers that enter at soil line, lay eggs and watch the larvae consume inner layers of bark. The larvae are protected from sprays by outer bark, and the areas they consume die for lack of nutrients. I’ve tried planting chives around the base of these trees to repel adults, and it seems to work for a few years, but not permanently. Some folks advise using moth balls as systemic controls, but if you want to eat the fruit, you’d be eating those dangerous poisons, too.

Control depends on what the destructive disease or creature is. V-shaped notches in leaves are made by black vine weevils. That’s only cosmetic damage, but it tells you that their larvae are in the soil eating roots. If numerous, they can kill a mature rhododendron in one season. Control of them is probably best done by inoculating the soil with beneficial nematodes. They will kill those destructive larvae without harming the beneficial microorganisms in the soil.

I’m a fan of biocontrol (one creature controlling a different creature), because insects may develop a tolerance for a chemical control, rendering it useless, but they can’t develop a tolerance for destruction by other insects – spiders, snakes or birds, for instance. Moreover, some beneficial insects can find destructive insects faster than I. I patrol my garden in company of paper or mud wasps, who are watching for newly hatched larvae to feed their own young. Those wasps can nick them out of broccoli or from tomato plants before they’ve done any damage at all. In spring and early summer, those wasps also feed on aphids. Unfortunately, their lives and appetites are winding down by late summer, when the gray cabbage aphids appear in large numbers.

There will be more about this next week, but please don’t spray toxic chemicals on your soil without full knowledge.

Send garden questions to or Gardening, The Statesman, P.O. Box 40, Boise, ID 83707.