Dormant Oil Spray

With spring well on its way, our favorite fruit trees will soon be in full bloom, and before we know it, they’ll be loaded with deliciously sweet treats! Unfortunately, we’re not the only ones who like to enjoy the fruits of our tree’s labor. Many overwintering pests like to hide out in our trees all winter long, just waiting for the opportunity to destroy our favorite crops. Luckily, with low-impact pesticides like dormant oil spray, we can easily control pest populations, without the risk of tree damage.

What is Dormant Oil Spray?

Dormant oil spray is a horticultural oil product used to control harmful pests on certain plants, usually fruit trees. Some consist of refined petroleum, while others are vegetable-oil based. The term “dormant” comes from the time of year that it’s applied – while the tree is deep in hibernation and won’t be affected by the heavy oils. However, there are some newer, lighter oils that are fine to use at any time of the year.

These oil sprays are safe to use on trees but penetrate the hard outer shell of overwintering insects, like aphids, scale insects, and spider mites, along with their eggs. The product smothers and kills them, preventing future pest problems during the growing season. Although it may not completely eliminate these insects, it does help control the population, ensuring your trees can blossom and fruit without risk of major pest damage.

What Plants to Spray with Dormant Oil

Dormant oil spray is intended to be used on fruit trees that are known for harboring these nasty pests. Apple, crabapple, pear, and plum trees are common targets and can especially benefit from a treatment of oil spray. While other fruit trees might not usually be affected, they won’t be damaged by the oil either, so it’s fine to spray as a precaution.

Be careful not to spray trees with bud breaks or young leaves and avoid using it on cedar, maple, juniper, or spruce trees – they’re more susceptible to damage from the oil!

When to Use Dormant Oil Spray

The most important direction for using dormant oil spray is to apply it when the tree is in its dormant stage! Fruit trees enter dormancy in late fall after their leaves have dropped – usually in November. The length of their inactivity actually depends on the weather, as they need a certain amount of “chill days” before they wake from their hibernation. Once they’re content with what our frigid Minnesota winter has provided, they awake in the early spring.

While dormancy might seem like a long period of time to get around to oil spray application, the window is much smaller than you’d expect. Oil spray will be less effective if it’s applied when temperatures are below freezing. The trick is waiting for that sweet spot in late winter/early spring when the temperature is at least above 40℉, but the buds haven’t begun to swell just yet. Wait for a dry day, since moisture can also make it less efficient.

How to Use Dormant Oil Spray

Once you get the timing right, the application is actually pretty simple. On a nice, dry spring day, pour your oil solution into a sprayer and head to the garden. Starting from the top branches of the tree, begin coating the branches, stems, and leaves, slowly working your way downwards. Make sure to get both sides of the leaves and all the crevices that pests like to hide out in since the oil spray only works if it comes into contact with the insects.

Is Oil Spray Harmful to Beneficial Insects?

Sometimes we forget that not all bugs are bad and not all insects are pests. Luckily, you don’t have to worry about harming beneficial insects, like pollinators and earthworms, with oil spray, because they aren’t around at the time of application! Spraying during dormancy not only protects the tree, but it also ensures that only insects that dig in for the winter just to wreak havoc in the spring, are targeted.

If you’ve got children and pets in your garden, don’t worry. Dormant oil spray has very low toxicity to humans and animals. In fact, it doesn’t leave any harsh residue!

Since we’re already a few weeks into spring, there isn’t much time left before the buds on your fruit tree begin to break. Pick up some Dormant Oil Insect Spray form our plant pharmacy today to make sure you get a handle on nasty pest populations this year!