by Jonathan Teller-Elsberg
Whether or not you’ve read Rachel Carson’s classic book, Silent Spring, you likely know the basic gist that synthetic pesticides have nasty, unintended side effects. This is true for insecticides, fungicides, and all the other –cides (from the Latin for “killer”) marketed to growers as the solution to disease and pest damage. In 2007, the most recent year for which the EPA provides data, approximately 20 percent of all pesticides in the U.S. were used outside of agriculture (meaning largely in gardens and yards), amounting to the release of 173 million pounds of active ingredients.
The chemicals with the most disturbing and far-reaching side effects are those that come out of the petrochemical industry. While the DDT of Carson’s era has since been banned for agricultural use throughout the world, numerous synthetics continue to be used both in commercial farming and home gardening. That said, non-synthetic compounds (whether or not qualifying as organic) can also be rather dangerous to “non-target organisms,” whether human or beneficial insect, fungus, or bacterium.
To reduce or eliminate your reliance on garden chemicals, begin with a long-term, preventative perspective. For example, give fruit trees and shrubs enough space to allow good airflow, which reduces moisture on leaves and fruit, thus reducing risk for many fungal infections. Similarly, be sure to prune properly, which helps with airflow as well as letting sunlight penetrate the canopy. Choose disease resistant cultivars. Plant a wide diversity of suitable companions under and near your fruit trees and shrubs, such as those that support beneficial insects. Apply woodchip mulch and the appropriate compost to promote healthy soil biology, which in turn strengthens your plants ability to resist and cope with disease; note that woody plants benefit from different compost than do annual garden vegetables, specifically, compost dominated by fungal rather than bacterial biomass.
Until your long-term strategies come into their own (and even after), you may still be confronted by the occasional insect onslaught or damp, disease-prone season. Even then, before utilizing a chemical spray, consider the first alternative of simply doing nothing. How much damage will the insect or fungus you are faced with cause? For example, you won’t win a prize for prettiest apple if you have flyspeck (caused by the fungus Zygophiala jamaicensis) but the fruit will still be perfectly edible. Each of us must judge for ourselves what level of aesthetics and quantity of harvest is worth the labor, cost, and possible health hazard of a spray solution.
The fact remains that some plant pests and diseases are potentially severe and require an active response. The first rule is to make sure you know what you are up against: just because you see an insect on your tree doesn’t mean it’s the species causing harm. Often, harmful insects can be held at bay with traps and other low-impact techniques. If push comes to shove, you might feel the need to nip fungal diseases in the bud with copper or sulfur.
Despite the title of this article, the act of spraying is not itself a problem. To learn more about promoting orchard health, I strongly recommend Michael Phillips new book, The Holistic Orchard. As part of his regimen for promoting orchard health and disease resistance, he recommends a variety of beneficial sprays that include such things as whole Neem oil and effective microorganisms.