Dormant oil spray is used to protect trees and plants from insects that try to attack and eat newly growing buds and leaves. This spray is typically applied near the end of winter months when plants begin to grow again and are at their most vulnerable to insect attacks.
Dormant oil works by suffocating or penetrating and destroying insects and mites that live on trees and plants. If dormant oil is used after buds and new leaves begin to grow, it kills the pests but it may harm the new buds and leaves. Dormant oil is relatively safe to use and affects a wide variety of pests while not harming plants or trees when used correctly.