More organic fruit tree sprays exist than the novice orchardist might initially suspect. These sprays, whether home-brewed or store-bought, protect against specific insects and plant diseases. Check with your nursery or extension service to determine which problems are most likely to face your type of fruit tree and climate, and arm yourself with one or more organic fruit tree sprays.
"Rodale's Ultimate Encyclopedia of Organic Gardening" recommends applying a spray made from kaolin clay and water to combat plum curculio. These insects, which feed on the fruit of several fruit trees and shrubs, also sometimes cause the fruit to drop before ripening. Kaolin clay spray also repels other insects, including leaf-feeding beetles, and additionally provides protection from some air-borne plant diseases.
Bacillus thuringiensis, or Bt, are natural bacteria that kill the larvae of several garden pests, including those that harm fruit trees. The bacterial sprays are considered organic because they contain no chemicals and target only certain garden pests, rather than birds, mammals or beneficial insects. Manufacturers offer several strains, each geared to separate groups of garden pests. In the fruit orchard, Bt combats the codling moth, the green fruitworm and peach tree borers, among others. Seek out the Bt strain that targets the insects attacking your fruit trees. The Rodale volume cautions that in many states certified organic farmers cannot use the spray because the bacteria are created through genetic engineering. Others believe products such as Bt offer an earth-friendly alternative to harmful pesticides.
Prepare compost tea buy soaking a burlap bag filled with compost in a large container of water. Let the mixture steep for at least two weeks. The resulting nutrient-rich liquid makes an effective spray that not only delivers nutrients directly to the trees' foliage, but also helps protect apricot, peach and plum trees from brown rot.
Mix 1 cup of vegetable oil with 1 tbsp. liquid soap, then dilute 2 1/2 tsp. of the mixture in 1 cup water. This homemade formula mimics the effects of commercial dormant oil and summer oil sprays. Oil sprays cut off the oxygen supply of young insects and also prevent insect eggs from hatching. Because these products are petroleum-based, some--but not all--organic gardeners avoid them. Use either the plant-based homemade formula or the petroleum-based commercial products to control harmful pests.
Garlic and Hot Pepper Sprays
Many organic gardeners rely on an all-purpose homemade spray to deal with a variety of insects. Because they are inexpensive and simple to create, you may wish to try them as your first line of defense against orchard pests. Blend 1/2 cup hot peppers with 2 cups water, strain and pour into a clean spray bottle. Alternatively, soak a dozen chopped garlic cloves in 1 pint mineral oil for at least one day. Strain and pour the infused oil into a clean spray bottle. If the mixture is too thick, dilute with water.
Derived from the exotic neem tree, neem spray helps repel a variety of orchard enemies, including the apple aphid, codling moth and oriental fruit moth. The spray is considered safe even on harvest day, according to Virginia Tech's "The Virginia Fruit Page" website. Avoid spraying near ponds, because neem is toxic to fish.