Nectria Canker

In maples, oaks, and ash trees across the Puget Sound region, look for slightly sunken lesions on twigs and limbs where wounds have occurred. The true giveaway is the appearance of striking orange-red fungal fruiting bodies clustered across the cankered area, making the problem unmistakable once it develops. Cankers can girdle entire branches or limbs, causing everything beyond them to die. In young trees, this translates to significant branch loss and structural damage.

The practical reality is that timing matters enormously: wounds created in late summer or fall provide entry points when the tree's defense systems are slowing down, so you'll see infection establish over winter and become obvious the following growing season. The management take-home is to prune only during dry weather near the end of dormancy, never in fall, and make clean cuts that heal promptly without leaving stubs where fungi can establish.