When to Spray Apple Trees for Insects

Updated November 22, 2016

Nothing tastes better than biting into a crisp, sweet apple from your tree - until you encounter a worm. Unfortunately, apple trees are susceptible to an assortment of insects, including moths, flies, aphids and mites. These pests lay eggs that develop into larvae, which are sometimes referred to as worms. The worms feed on the flesh of the apple, or the leaves and bark, until they develop into the adult insect and start the whole cycle over again. Spraying an apple tree with the right chemicals, at the correct time, can eliminate these pests.

Before the Bloom

At the first signs of green growth on the apple trees, use a horticultural oil spray, easily found at any garden centre, following the application directions on the label. A horticultural oil spray will suffocate any scale insects and mite and aphid eggs that survived the winter. At the same time, a fungicide spray can be applied to control any fungus problems that may have developed over the winter. Never spray pesticides on an apple tree when it is in bloom. Doing so will kill the bees that are pollinating the blossoms.

After the Bloom

After the bloom, when 90 per cent of the apple blossoms have lost their petals, a homeowner can begin to spray with a premixed fruit tree insecticide that will control a variety of pests, including chewing insects, sucking insects, and diseases. (see Reference No. 1) Follow the application instructions on the label. After this initial spraying, repeated applications will be needed every one to two weeks while the fruit is growing. Stop spraying two weeks before harvesting the apples.


Insecticides and pesticides are poisonous, so great care and caution should be taken when using them. Over the years, apple tree pests can become resistant to chemicals, therefore, only use sprays as directed and always at the prescribed mixture.

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