Dormant Oil Application in October: Protection from Insect Damage for your Landscape Trees & Shrubs

Dormant Oil is a known application that is sprayed on landscape trees and shrubs in fall to help protect them from overwinter damage from insects. Prepared from a mixture of highly refined petroleum oils combined with an emulsifying agent, dormant oil can be mixed with water and sprayed on trees killing exposed insects and mites by either suffocating them or destroying internal cells. These oils are effective in controlling most species of scales and mites that overwinter as nymphs or adults such as cottony maple scale, obscure scale, euonymus scale and lecanium scale which can do early damage. Dormant Oil is also effective on insect eggs that are laid in September and overwinter such as aphids, leafrollers, Spruce Spider Mite, Honeylocust Mite and European Red Mite. Dormant Oils are effective for both immediate and preventive care and have been developed to be less harmful to beneficial insects.   They are also safe for birds, humans and other mammals.

When to Apply:  Dormant oil applications should be applied in fall when temperatures remain in the 50’s at night (Early October) and must be done when temperatures stay above freezing for 24 hours. Dormant Oil is also best applied on a clear day with no wind and no threat of rain within a least six hours so that the oil can dry.  It is preferable to choose a time when no rain is in the forecast for a few days to ensure effectiveness.

Warnings:  Be sure to follow all label directions because oil sprays may damage certain plants, including Japanese maple, Eastern Redbud, sugar maple and Amur maple.  It can also cause the foliage (needles) of Colorado blue spruce to become discolored (change from blue to green) since the pigment is formed from the oils on the surface of the plant.  When in doubt consult with your landscape professional.

Dormant Oil when applied correctly will help to protect your trees and shrubs from winter and early spring harm from a variety of damaging insects and will ensure the health and vitality of your landscaping.

For more information on dormant oil application visit:  Colorado State University horticulture Insect Control

As Always..Happy Gardening!

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Dormant Oil: October Landscape Maintenance

garden tips
DORMANT OIL APPLICATION:
Welcome to Fall!  It’s time to spray your trees with dormant oil.  Dormant oil protects your ornamental trees, shade and fruit trees by placing a protective coating on the surface smoothering out any insect larvae that can hatch in the spring and do damage to your plants. Dormant oil is an important tool to manage certain pest problems such as scales, aphids, whiteflies, caterpillars and mites during the winter while your plants are dormant.

 

WHEN TO APPLY:
Spraying of dormant oil should occur on a clear day when the temperatures are expected to remain over 50 degrees F. for at least twenty-four hours. The ideal temperatures for application is between 40 and 70 degrees F.

 

WHAT INSECTS ARE CONTROLLED BY OIL?
Aphids
Tent Caterpillars
Scale
Spider Mites
Leafhoppers
Whiteflies
Mealy Bugs

 

PRECAUTIONS:
Always read directions before application.  Avoid using on plants that are oil-sensitive.

 

SOME PLANTS KNOWN TO BE OIL SENSITIVE:  (Read Directions on Bottle)
Cryptomeria
Junipers
Weeping Japanese Maple
Eastern Redbud
Dwarf Alberta Spruce
Black Walnut
Douglas Fir
Hickories
Smoke Tree

 

Having a regular spray program with proper care of your plants will increase the long-term health and vitality of your landscape and possibly eliminate any major damage due to invasive insects.  Happy Gardening!

 

Author: Lee@Landscape Design By Lee, 2013, All Rights Reserved

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