Most often, trees weakened by other factors or pests are the most susceptible to infection. These diseases caused by parasitic fungi lead to reduced growth, wood decay, and even death. The mushroom caps are honey yellow and the top of the cap can be sticky while the underside of the cap has white spires and gills. Another characteristic of Armillaria infection is bark with rot that appears white. Armillaria root disease affects trees, shrubs, and herbaceous plants in a variety of ecosystems. To help identify Armillaria infection, two-inch-or five-centimeter-tall mushrooms with yellow or brown stalks grow near the base of the infected tree. A lookalike disease is brown-spot needle blight, caused by the fungus Scirrhia acicola, and the two can only be distinguished under a microscope.ĭiseases ailing tree roots include Armillaria root disease, black stain root disease, laminated root rot, and Schweinitzii root and butt rot. These diseases can be more difficult to diagnose as only the roots, which are underground, show infection. On the West Coast, these bands can be bright red which is why this disease is also known as the “red band” disease. It may take a year for the infected leaves to fall, but the tree will eventually die after successive years of infection. Below are some common diseases we find here in Washington State.ĭothistroma needle blight is caused by Dothistroma pini, a fungus that causes pines to defoliate prematurely. In the United States, needle blight affects 20 different pine species and can be detected by deep green bands on needles that fade and turn brown over time, as well as yellow spots. The leaves, roots, or branches of various tree species can become infected with diseases that lead to wood decay, reduced growth, and even death.

There are also plenty of diseases that can harm them. Known as the Evergreen State, Washington is replete with many different species of trees.

Tree identification pacific northwest