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Early Spring Insect Control With Horticultural Oil


Did you know that late winter and early spring is one of the most effective times for insect treatments on your trees and shrubs? With the chill of winter still in the air and most plants without leaves or flowers, most people are not thinking about insect treatments or insect problems. However, a well-timed application of horticultural oil when trees and shrubs are still dormant can prove very effective in controlling insect pests.

Why is the late winter or early spring a good time to use horticultural oil? Horticultural oil can be applied almost any time of year, but when applied in the dormant season it can be used to kill many overwintering insects and their eggs before these populations have started to grow. This helps to control or stop the problem before it ever even starts. Some insect pests and their eggs are especially vulnerable when overwintering so the dormant oil spray is most effective. In addition, many beneficial insects and mites are less likely to be harmed.

What is horticultural oil and how does it work? Horticultural oil is a highly refined oil that is toxic to many insects and their eggs but is very safe to use for humans. It works by smothering pests and interfering with their cell metabolism. The residual activity of horticultural oil is very short, which helps minimize it effect on beneficial insects that can help protect your trees and shrubs.

What insect pests of trees and shrubs can be treated with horticultural oil? Horticultural oil sprays are effective against a number of soft-bodied insects, mites, and their eggs. These include aphids, adelgids, a number of different mite species, honey locust plant bugs, lace bugs, leaf miners, psyllids, some scale species, and spider mites, to name some of the more common uses.

What are the benefits of treating insect pests with horticultural oil? Horticultural oil has a number of strong attributes. The first one is that it works! As mentioned, a number of insect pests that damage trees and shrubs can be effectively controlled with horticultural oil. Second, it is very safe for humans, pets, and the environment. Third, it is relatively inexpensive yet very effective, making it a very valuable treatment option. And lastly, it is light on non-target insects that can actually be beneficial for keeping your trees and shrubs healthy.

Tips for using horticultural oil. To be effective and safe, it is important you have a licensed and well-trained applicator (such as those we employ) do your treatments. If not done properly treatments can be ineffective and actually damage your plants. First, timing is very important in doing treatments. If doing a dormant treatment, trees must actually be dormant to avoid harm and temperature must be above freezing for at least 24 hours following treatment. If treating during the growing season, timing the treatment with the activity of the insect is crucial to be effective. Also, spraying during high humidity should be avoided to prevent plant damage, and certain plants, such as blue spruce, should not be sprayed with horticultural oil. All of our applicators and certified arborists are well trained and licensed to be sure that our treatments are both safe and effective.

How do I know if my trees and shrubs would benefit from a treatment with horticultural oil? The best way is to get your property evaluated by one of our ISA certified arborists. We would be happy to walk your property and identify any trees and shrubs that could benefit from fertilization or insect and control treatments. We keep up to date on all of the latest insect and disease control research to ensure that we can help your trees and shrubs look their best. Please feel free to call or fill out an estimate request to get a free property assessment on the health of your trees and shrubs.