Dormant sprays are an important part of maintaining healthy fruit trees and should be applied yearly to protect your trees. While most types of sprays are meant to be used during the growing season after problems begin, dormant sprays are applied during the winter months and are meant to prevent the problems from occurring in the first place.
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Types of Dormant Sprays
Dormant sprays are a group of pesticides that control either insects or diseases. Dormant oils control insect pests by creating a thin oily coating on the dormant branches that smothers overwintering adult pests and their eggs. Copper sprays control diseases and are used at different rates for the dormant season and for the growing season. Dormant rates for copper sprays are much heavier than growing season rates, which makes them more effective in the dormant season. You can mix the two types of sprays together, and they sometimes come pre-mixed.
Trees That Benefit From Dormant Sprays
Treatment of fruit trees is the most common use for dormant sprays, although other disease-prone trees and shrubs, such as dogwood trees and roses, can benefit from yearly spraying. Only trees that completely lose their foliage and go dormant during the winter months should receive dormant spray treatments. Look for signs of disease or insect damage during the growing season to identify dormant spray candidates for the next winter. Trees that are normally disease prone, such as peaches and cherries, will benefit from being sprayed every year.
The Dormant Spray Window
The dormant spray window is the time from late fall through late winter, after the foliage has fallen off, but before the buds begin to swell again in the spring. Applying dormant spray to trees that are actively growing or beginning to flower can affect the production of fruit by damaging the emerging flowers or disrupting pollinators in the area. Also, applications during below-freezing temperatures can cause damage to the bark, especially if it is thin or delicate.
Dormant Spray Schedules
Apply dormant sprays at least two to three times during the dormant spray window, at four- to six-week intervals. You may begin applying dormant spray as soon as the leaves drop in the fall, which gives you time for three to four spray intervals before the buds begin to swell. At the very least, you should spray twice during the dormant season. Spraying only once or twice is still better than not spraying at all, but three times is ideal.