Gardening with Allen Wilson: Spray fruit trees now for insect, disease prevention

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

Begin spray applications as soon as the flower petals have fallen from 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 that are pollinating the flowers.

Peach, nectarine and some cherry trees are susceptible to peach leaf curl disease. It is critical to get a fungicide on as soon as the leaves begin to open. Peach trees almost always get this disease unless they are sprayed. It will damage trees and greatly reduce the fruit crop if they are not sprayed.

Scab is the main disease affecting apples and pears. It produces scab-like deformations on both the leaves and fruit. Two applications spaced a week apart after petals 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 hang 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 that do not have traps.

Start spraying cherry and plum trees for fruit fly maggots when fruit is about half size. Spray every two 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. Lime sulfur is best for peach leaf curl.

My favorite insecticide is an organic one called spinosad. It is available in three or four brands of garden insecticide (Ferti-lome, Bonide, Monterey). Check the ingredients label. Traps and spinosad are usually available only in full service nurseries and garden stores (not chain stores) or online.

Fruit tree sprays containing both insecticide and fungicide are also available, although they are not usually organic.

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