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Dormant Oil – What You Need To Know!

man spraying tree with oil

Have you ever heard of dormant oil before? Many people recommend using it in the late winter/early spring on certain trees. If you are not very familiar with dormant oil, you may be asking yourself what exactly is it and how do I learn more about it? No worries if you’re a bit puzzled, we are here to give you all of the details about dormant oil!

So what is dormant oil and what is it made of? Dormant oil is a horticultural oil that is sprayed on plants and trees when they are dormant to help control insects. It can be used on many different trees from fruit trees to lilacs. These sprays are typically made from petroleum oil, with some being made from cottonseed oil and are much more refined than they were in the past.

How exactly does dormant oil work? The oil either suffocates the insect or destroys their cells. Some of the mites that can be controlled include the honeylocust, European red, and spruce spider mites. It is extremely important for dormant oil to be used at the correct rates and on the correct trees in order to not kill the leaves or cause any damage to them. It should only be applied when temperatures have been above freezing for at least 24 hours. These oils can certain scales that overwinter including cottony maple, euonymus, lecanium, and obscure scale. Summer oil applications are sometimes needed as well.

What are the advantages and disadvantages of applying dormant oil? Some of the advantages of applying dormant oil include a small chance of insects developing a resistance to it, they are generally less harmful to beneficial insects than other pesticides are, and they are generally safe to humans, birds, and mammals. The potential disadvantages are that there can be plant damage if it is applied incorrectly and minimal residual activity killing any new insect infestations.

Hopefully, you now have a better understanding of dormant oil and its use, and the advantages and disadvantages. If you are worried about insects attacking your trees this winter, you may want to consider an application of dormant oil!