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Dormant Oil Application

Updated: Mar 9, 2021

Apply dormant oil before bud break to prevent overwintering pests & diseases.

​To control overwintering insects and diseases on fruit trees and other deciduous (non-evergreen) trees and shrubs, spray them with dormant oil during their winter’s sleep. This organic pesticide works to kill any exposed insects AND diseases. Common targeted insects include scale insect, spider mites, caterpillars and their exposed eggs. It also does a great job controlling common diseases on fruit trees such as peach leaf curl, apple scab and powdery mildew. Use on roses to reduce black spot. This dormant spray solution is less harmful to pollinating insects and other beneficial bugs as they are not around this time of year. And unlike other pesticides, the insects and fungi do not develop a resistance; a common issue especially when using fungicides. Apply while plants are still dormant and have not yet sprouted foliage or buds. Spray when there is no rain, snow or frost predicted for 24 hours. Temperature should remain at 0°C (32°F) or above for at least 24 hours. Avoid spraying on evergreens (cedars, rhododendrons etc.) as it may injure them. Apply in the morning so the plant will be dry by evening. Don’t apply if frost is predicated overnight. Although this sounds like the window of applying this organic pesticide and fungicide is rather narrow, it's usually doable. And it works. You will notice a huge difference in fruit trees especially if dormant oil applications have been neglected. Usually the end of February to the middle of March is the window of opportunity for this application.

Dormant oil is created from filtering impurities out of petroleum and is used to kill plant harming insects before trees start to bud.

There are advantages and some disadvantages to using dormant oil.

Advantages of Dormant Oil

  • Gets rid of most species of mites and scales

  • Low likelihood of insects developing a resistance

  • Less harmful to beneficial insects

  • Safe for birds, humans and pets

Disadvantages of Dormant Oil

  • Potential plant damage if incorrect oil is used or applied during growing season

  • Only kills current pests wi th minimal residue remaining to affect future pest invasions

Protect Your Trees with Dormant Oil Treatment

As mentioned it’s very important to read the labels on oils before applying them to trees. Oils used on the wrong trees can cause major damage and destroy the appearance of the tree. Oils are best if applied when the temperature is going to remain above freezing for over 24 hours, however it’s usually better to wait until right before the growing season starts because dormant oils can speed up spring bud development.

It is also recommended to use dormant oils with large amounts of water to make sure that all cracks in the tree bark are covered. As with any other type of tree or shrub application it is always recommended that applications be handled by a trained and licensed professional. Applications not done properly can at time cause more damage than benefit trees and shrubs.

One Call Property Solutions specializes in protecting trees and helping them grow large and healthy. Our tree service can ensure that your trees are insect free and that all oils and chemicals used are safe and healthy for your trees.

Contact us today by phone or text to (208) 490-6713. Or request an estimate at

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