Editor’s Note: Interested in free weekly updates from Northern Michigan? Sign up for the WEEKLY PINE VIEW
REGION– If your hemlock trees show signs of hemlock woolly adelgid, now is the time to plan treatment. This invasive insect feeds on tree sap and can kill hemlocks within four to 10 years if left untreated.
Effective treatments include products with imidacloprid or dinotefuran. Imidacloprid works more slowly but protects trees for several years, while dinotefuran acts quickly and is best for heavily infested trees. Most products can be applied to the soil near the trunk and absorbed through the roots.
Treatments should be applied between early April and late October when soil conditions are right. Be sure to follow all label directions—these are legally required—and take care to prevent runoff into water sources.
Homeowners can often treat trees themselves, but a licensed professional may be needed for large trees, sensitive areas, or more advanced methods like trunk injections.
After treatment, monitor trees yearly and plan for retreatment as needed. Early action is key to saving your hemlocks and protecting surrounding landscapes.
