Dormant Oils – a Proactive Approach to Insect Control
It’s January…
Lawn care professionals and lawn enthusiasts appear to be singularly focused on one thing: Appling pre-emergent herbicides to prevent annual weeds from germinating this spring!
But wait…
Isn’t there something else we should be focused on?
Isn’t there also a way to prevent insects from overtaking your trees and shrubs this spring and summer?
Yes! You should also be applying Dormant Oils to trees and shrubs now.
A Dormant Oil Application now is to insect control what a Pre-emergent Herbicide Application is to weed control.
What is Dormant Oil?
Dormant Oils are an eco-friendly, effective way to control overwintering eggs and insects.
Commonly referred to as Dormant Oils, but technically they are Horticultural Oils. The common name Dormant Oils came about because they are sprayed on trees and shrubs while they are in dormancy before buds open in the spring.
Dormant oils are not poisonous or harmful to humans or pets.
Oak Scale, also known as Soft Scale is a common pest on oaks and cause stunting and twig dieback. A dormant oil application is the first step in controlling the pest.
Aphids are small sap-sucking insects that excretes a large amount of sticky honeydew May through September. A dormant oil application will help smother aphids eggs that overwinter on branches.
How does a Dormant Oil work?
Dormant oils work by suffocating and smothering overwintering insects. Oil blocks the air holes causing the insect to suffocate. In some cases, the oil acts as a poison and at times the oil can interfere with how an insect feeds.
White scale on crape myrtles.
What insects do Dormant Oils control?
Dormant oils typically target two types of insects, sucking and chewing pests.
Dormant oils control scale insects, aphids, some borers, and mites that are overwintering on trees and shrubs. They also can be effective as a fungicide to combat powdery mildew, leaf spot, and rust.
Two pest dormant oils target have become a common problem in our landscapes: scale and aphids.
Scale – White bark scale on crape myrtles is a problem in central Oklahoma. The insect is invasive and results in a black mold along the branches and trunk. Although the scale is rarely fatal to the plant, they are responsible for stunted growth, reduced flowering and decreased aesthetics.
Aphids – A few aphids are not a problem and do not require treatment. But if populations increase, they can cause damage. Application of dormant oil in the late winter or spring is the best preventive step to control aphids and is recommended.
Crape myrtles often struggle with scale and aphids and benefit from an annual dormant oil application.
The first sign of a spider mite problem is a plant that is showing signs of decline and the foliage takes on a yellow cast. Dormant oils can be used to kill mite eggs.
Spider mites are very small pest visible as small pepper sized specs that move on a white sheet of paper. Dormant oils can be used to kill mite eggs.
When should Dormant Oils be applied?
Applications should be made from winter to early spring while trees and shrubs are dormant.
The goal is to make the application while the plants are hardened off over the winter and before new buds or shoots start growing in the spring.
Treatments should be made when temperatures are above 32 degrees and winds are light.
Even coverage of all branches is very important to ensure the oils coat insects.
Do not spray on wet plants.
Always read and follow the label before spraying. Some plants, such as blue spruce and blue juniper, can experience temporary loss of color if sprayed by Dormant Oils.
“Right now, is the perfect time to take care of overwintering pests hiding in your trees and shrubs. Hall | Stewart’s Tree & Shrub Care Program Application #1 includes dormant oils. It is the easiest and most effective way to keep scale, mites, aphids, and other overwintering insects under control before they cause problems this spring and summer.”
Trinity Baird, Hall | Stewart Tree & Shrub Care Specialist
Dormant oil applications are an effective way to control scale on trunks and branches.
White scale on crape myrtle is a problem in central Oklahoma. If you have crape myrtles in your landscape, a dormant oil application is recommended.
Who Should Schedule A Dormant Oil Application Now?
Anyone who has struggled with aphids, mites or scale in the past year.
Anyone desiring an eco-friendlier approach to insect control.
Anyone who wants to reduce insect populations now instead of waiting until the growing season when harsher control methods are required.
Protect your landscape investment with a Dormant Oil Application this winter!
Lorne Hall
Hall | Stewart Lawn + Landscape
(405)367-3873