Dormant oils will help control problems like scales.

This plant is infested with scales, which is one type of pest that you can use dormant oils on. You would want to spray while the plant is in its winter slumber.

You may have seen tips that a round of dormant oils is useful at this point in the year to help control pests. What are they and why would they be useful?

What Are Dormant Oils?

Dormant oils are usually formulated using petroleum as a base. It is called a dormant oil because of the time when you are supposed to apply it. Some types are now able to be used at other points in the year due to advances in manufacturing. They are used on a wide variety of plants, trees and shrubs.

When you spray it on an insect or mite, it coats their body and keeps them from being able to breathe. Some formulations directly damage certain insects, further leading to their demise.

What Pests Are Affected by Dormant Oils?

These oils are typically sprayed on plants to fight pests like aphids, caterpillars, mites and scales. I had to use some horticultural oil when my container peach tree was attacked by red spider mites. I have also used it to try and fight a double dose of aphids and mealybugs on a banana tree houseplant. If I had used a dormant oil on the peach tree at the right time of year, it may not have had that problem.

Some pests can be harder to control than others. Scales can be especially difficult sometimes since some have an armored exoskeleton that is difficult to penetrate. You may need to apply more later in the growing season when the insects and their young larva may be more susceptible.

Why Do You Use It While the Tree is Dormant?

You are trying to catch any insects that made the plant their home during the winter. Some plants do not do well if dormant oils are used while they are actively growing since the oils can damage their leaves and other parts. When the plant is dormant, there is no foliage present, so it is safer to use.

What plants do you use dormant oils on? What type of pest?