There are two common myths about the future of our hemlock trees when it comes to hemlock woolly adelgid. They are 1) there is nothing you can do and 2) treatments are too expensive to be practical. If you have trees in your yard or in your favorite natural area, they can be treated with the right resources. Let’s go through some of the steps.

Take the limbs of your hemlock tree and turn them over. You are looking for white cotton like masses along the twigs and at the base of the needles. The image to the right shows the underside of an infested branch.

Trees can be systemically treated with an insecticide containing the active ingredient Imidacloprid. Systemic treatments allow the insecticide to move with the tree sap and are consumed by HWA as they feed. These types of treatments may remain effective for 2-5 years. There are three methods for applying systemic insecticides: 1.) soil drenching, 2.) soil injection, 3.) trunk injection. Trunk injections are not recommended. Soil drenching and soil injections, when applied properly, are the most effective treatments.

Trees may also be sprayed with insecticidal soaps and horticultural oils during March through April and from September to October. This type of treatment may be needed during both the spring and fall or at least annually. If trees are not thoroughly covered or trees are too tall for available equipment, the surviving HWA will soon reinfest the trees. This method will kill any beneficial insects on your tree and is not guaranteed to save your hemlock from HWA.

Please contact us with any questions.