Organic gardening strives to use natural alternatives to traditional chemical pesticides in crop production. This includes the growing of tree fruits, including peaches, cherries and other stone fruits, citrus, apples, and pears. Many of these approved pesticides are derived from botanical sources, while others are mineral-based or biological in nature. When properly applied, these naturally occurring pesticides can help to reduce the damage done by insect pests while maintaining an organic approach to agriculture.
Nicotine Sulfate
Extracted from the tobacco plant, nicotine sulfate is an effective neurotoxin for controlling insects on fruit trees. Among the oldest of organic pesticides, it waned when cheaper synthetic pesticides were introduced. Now, with the resurgence of interest in organic food production, nicotine sulfate is once again in use. This insecticide breaks down much more quickly than synthetic pesticides and is effective against aphids, thrips, mites and other insects that attack fruit trees.
Neem
The Cornell University Resource Guide for Organic Insect and Disease Management identifies products of the neem tree, or Azadirachta indica, which is a plant native to southern Asia and India that has been used for centuries as a pesticide, among other applications. Neem products are becoming more popular in Western regions as an effective organic pest control for fruit trees. Containing a natural pesticide called azadirachtin, neem, in the form of soap or oil, kills aphid species, leaf miners, caterpillars, mites and leaf hoppers.
Pyrethrum
Made from pyrethrum daisies, pyrethrum is another naturally occurring insecticide. Especially effective against aphids that attack peaches, plums and other stone fruits, as well as apples and pears, pyrethrum contains chemicals from which the popular synthetic insecticide Pyrethrin was derived. Examine the packaging carefully for pyrethrum-based products, as only a few are approved for use on organic crops. Colorado State University states that pyrethrum is nontoxic to mammals, which makes it one of the safest of pesticides.
Sulfur and Lime Sulphur
According the Colorado State University Cooperative Extension, both sulfur and lime sulfur, made from boiling lime and sulfur together, are used to protect fruit trees organically from several different problems. These include anthracnose blight; powdery mildew; rust; fruit rot; leaf blight; and some types of insects, including thrips, scales and certain mites. The downside to using these mineral treatments is the strong rotten egg smell they tend to give off. They can also damage fruit trees, if applied when temperatures rise above a certain temperature. Both are harsh and can irritate skin and eyes.
Rotenone
The Cornell University Resource Guide for Organic Insect and Disease Management also lists rotenone as an approved organic pesticide. A resinous material, naturally derived from the roots of certain plants, rotenone is effective on a wide range of insects, including beetles and especially soft-bodied insect pests such as caterpillars, aphids and thrips. Slow acting, rotenone may take several days to be fully effective. This organic pesticide is relatively toxic to mammals and lethal to fish.
Beneficial Insects and Bacteria
An unusual form of insecticide is actually using insects to kill and control other insects that are pests. According to Clemson University, lacewings, praying mantids, ladybugs, certain mites, wasps and other predatory insects feed on destructive bugs such as aphids, scale insects and other damaging insects. You can purchase many of these insect species, occasionally, at garden centers, and good sources are available online. Released into a fruit orchard, these insects can help to reduce the threat of insect pests without the use of chemicals. Several types of bacteria will also attack some insects, including Bacillus subtilis and Bacillus thringiensis, which are toxic to insects when eaten.
References
- Colorado State University: Some Pesticides Permitted in Organic Gardening
- Cornell University Resource Guide for Organic Insect and Disease Management: Rotenone
- Clemson University: Beneficial Insects
- Cornell University Resource Guide for Organic Insect and Disease Management: Bacillus Thuringiensis
- Texas Agricultural Extension Service: Texas Citrus, Concepts of Pest Management
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