This is a critical time of the year to get a head start on controlling some keys pests in the garden. Dormant oil helps to control aphids, scale, spider mites, and many other insects by desiccating or smothering eggs and larvae.
These sprays are applied usually between November to late March or early April …If your trees or shrubs have not yet leafed out then there is still time. Do not apply if the tree or shrub has leaves.
Most trees and shrubs will benefit from dormant spray. Fruit trees, raspberries, junipers, roses, and many flowering shrubs probably benefit the most. The main insects that dormant spray helps to manage are; aphids, blister mites, bud mites, scale, pear psylla, peach twig borers, lygus bugs, and many other insect’s eggs. Honeylocust mite, European red mite, and spruce spider mite are controlled with dormant oil sprays, because they overwinter as exposed eggs on plants. Dormant oil sprays do not kill two-spotted spider mite, as they overwinter on the ground in leaf debris.
Spray the upper branches, twigs and trunks of trees with dormant spray. Try not to not to spray the lower trunks with dormant spray because many beneficial insects lay their eggs in the lower parts of the tree.
Apply only when trees are dormant, usually November through April, after all the leaves have fallen. Mix with water as directed and spray to all surfaces of the trunk, branches and twigs. Apply when the temperature is expected to rise during the day. Spray the branches thoroughly; to the point of dripping. You may need 4 or 5 gallons of dormant spray to completely cover a large tree. Spray junipers, and other shrubs, thoroughly from top to bottom, to prevent many insects, such as scale or spider- mites.