European Canker Nectria Canker

On ornamental pears, watch for raised, reddish-brown cankers on main branches and the main stem, particularly in spring and early summer. These lesions may have concentric rings, and during wet weather you'll notice red fruiting bodies (like tiny pustules) emerging from the bark. Affected branches gradually decline in vigor, and if the canker girdles the stem, everything beyond dies back. This disease pressures ornamental pears throughout the Puget Sound region, especially when cool, wet springs persist.

Nectria canker thrives when trees are stressed or recently wounded by pruning, wind damage, or cold snaps. The fungus enters through fresh cuts and wounds, so the timing of pruning matters significantly. Remove cankered limbs during dry weather in early summer when the wood is healing actively and conditions favor quick closure over infection. Make clean cuts, and avoid heavy pruning that invites the disease in the first place. Once a major canker girdles the trunk, the tree is often beyond saving.