Spray Fruit Trees to Prevent Insects and Diseases

I want to make sure I do not have scab or worms in my apples this year. When to I have to spray to prevent these problems?

Begin spray applications as soon as the flower petals have fallen from the trees to protect apples and other fruit trees from insect and disease problems. Avoid applying insecticides before the petals have fallen because it will harm the bees which are pollinating the flowers.

With peach and nectarine trees it is critical to get a fungicide on as soon as the leaves begin to open. This protects them from peach leaf curl disease. Trees almost always get this disease unless they are sprayed. It will damage trees and greatly reduce the fruit crop in they are not sprayed.

Scab is the main disease affecting apples and pears. It produces scab-like deformities on both the leaves and fruit. Two applications spaced a week apart after petal fall will provide protection.

Worms in apples and pears and fruit maggots in cherries and plums can be prevented by regular insecticide applications. Begin spraying apples and pears as soon as petals have fallen. Direct the spray to the newly formed fruit clusters. Trees must be sprayed every two weeks until August first to provide complete protection from worms.

An alternative to spraying apples and pears is to apply codling moth traps in the trees. The codling moth is the insect which lays eggs on apple and pear fruit which bore into the fruit as worms. Traps are only partially effective, especially if you have a lot of nearby apple and pear trees.

Start spraying cherry and plum trees for fruit fly maggots when fruit is about half size. Spray every 2 weeks until harvest.

Fungicide and insecticide can be combined in the same application. My favorite fungicides are copper fungicide and lime sulfur (calcium polysulfide). Both are safe organics.

My favorite insecticide is a new organic called Spinosad. It is available in 3 or 4 brands (Ferti-lome, Bonide, Monterey) garden insecticide. Check the ingredients label. Usually available only in full service nurseries and garden stores (not chain stores) or on line.


Allen Wilson

Allen has been writing about gardening for over 30 years. He is a retired professor of Horticulture.

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