Answer: Dormant oil is a highly refined petroleum oil used primarily to control scale insects and the overwintering eggs of red spider mites and aphids. It is diluted with water prior to spraying. The oil coating suffocates these pests as well as their eggs. Insects cannot become resistant to it.
Dormant oil should be applied to fruit trees in early spring while they are dormant but just prior to bud swell. A dormant oil spray one week before bud break is most effective. The entire tree should be covered with a layer of the oil.
You'll find dormant oil in the gardening section of your local Home Depot.
Best wishes with your fruit trees!
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