Phomopsis Canker

Phomopsis lokoyae    (fungus)

Douglas fir trees throughout California and Oregon.

Malnutrition, improper irrigation, poor soils, construction stress, persistent rainy or foggy weather; wounding by squirrels, birds, improper pruning, and climbing spurs.

Long, narrow cankers on branches, usually pointed at ends; may girdle entire branch in one season. Usually in saplings on poor sites, but it may attack individual branches in mature ornamental trees under stress.

The fungus may enter through needle scars or wounds. It girdles branches and is usually successful in stressed trees. Cankers are established at the point of infection. During wet season, spores are produced in spore fruits (pycnidia) at the edges of the cankers from which they spread to other parts of the tree, or to adjacent trees.