Apples are prone to insect and diseases—including apple maggots, plum curculios, green fruitworms, and codling moths. Many gardeners who swear off pesticides find they need to find, at minimum, an acceptual annual spray treatment for a decent crop.
One idea to avoid pesticides is to select disease-resistant varieties such as ‘Prima’, ‘Priscilla’, ‘Liberty’, and ‘Freedom’. They do not require spraying for apple scab, cedar-apple rust, and other common diseases, while most other varieties require periodic spraying every spring and summer after planting. Check with your extension service to find approved pest prevention programs for your area.
You can also try an anti-insect oil, found at garden stores. Spray it in the spring when your apple trees are in the tight cluster stage: after the leaves have unfolded from the fruiting cluster, but before the buds begin to show pink.
Other pests such as scales, mites, and aphids should be controlled by natural parasite and predator populations if you haven’t used a lot of sprays.
The apple maggot can be trapped simply enough by hanging one or two round, softball-size balls—painted red and coated with sticky “Tangle-Trap”—from a branch in June through the summer. Reapply the sticky goo a time or two, as necessary.
Keep deer at bay with repellents, fencing, or deer-resistant plants; deter mice and rabbits with wire-mesh cylinders around the base of the tree.
To keep insects away from apple trees, make a solution of 1 cup of vinegar, 1 cup of sugar, and 1 quart of water. Pour this mixture into a widemouthed plastic jug. Hang the jug, uncovered, in your apple tree.
Fend off diseases by raking apple leaves, burying them beneath mulch, or grinding them with a lawnmower at season’s end