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Common Spring Tree Pests and Diseases: How to Spot and Treat Them


The Pacific Northwest is home to a wide range of tree pests and diseases that can cause damage to trees and landscapes. Some of the most common pests and diseases found in the region include Armillaria root rot, wooly adelgid, Douglas-fir beetles, bronze birch borers, and emerald ash borers.




Armillaria root rot is a fungal disease that attacks the roots of trees, causing them to decay and eventually die. It is prevalent in the Pacific Northwest and can affect a wide range of tree species, including conifers and hardwoods. Trees affected by Armillaria root rot may show symptoms such as yellowing leaves, thinning canopy, and a lack of new growth. To prevent the spread of Armillaria root rot, it is essential to remove infected trees or treat with organic fungicide and maintain good tree health through proper watering and fertilization.



Wooly adelgid is a tiny insect that feeds on the sap of hemlock trees, causing them to decline in health and eventually die. It is prevalent in the Pacific Northwest and can affect both eastern and western hemlocks. Symptoms of wooly adelgid infestation include yellowing needles, thinning canopy, and the presence of white, wool-like tufts on the tree branches. Treatment for wooly adelgid may involve organic insecticide sprays or systemic treatments.



Douglas-fir beetles are a common pest found in Pacific Northwest forests. They attack Douglas-fir trees, causing extensive damage to the bark and eventually killing the tree. Symptoms of Douglas-fir beetle infestation include yellowing needles, oozing sap, and the presence of small holes in the tree bark. Preventive measures for Douglas-fir beetles include maintaining healthy trees through proper watering and pruning, as well as removing any infested trees and using an organic systemic treatment.




Bronze birch borers are another common pest found in the Pacific Northwest. They attack birch trees, causing extensive damage to the bark and eventually killing the tree. Symptoms of bronze birch borer infestation include yellowing leaves, thinning canopy, and the presence of small holes in the tree bark. Preventive measures for bronze birch borers include maintaining healthy trees through proper watering and pruning, as well as treating with organic insecticides.




Emerald ash borers are a destructive pest that attacks ash trees, causing extensive damage to the bark and eventually killing the tree. While they have not yet been detected in the Pacific Northwest, they are a significant concern for tree care professionals and homeowners alike. Symptoms of emerald ash borer infestation include thinning canopy, bark splitting, and the presence of D-shaped exit holes in the tree bark. Preventive measures for emerald ash borers include early detection, quarantine measures, and organic insecticide treatments.


In conclusion, tree pests and diseases can cause significant damage to trees and landscapes in the Pacific Northwest. Early detection and preventive measures are essential to maintaining healthy trees and preventing the spread of infestations. At TreeMedics, our team of experts is equipped with the knowledge and tools necessary to identify and treat common tree pests and diseases found in the Pacific Northwest. Contact us today to schedule a consultation and protect your trees from harm.


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