Cytospora Canker of Spruce
Cytospora Canker is caused by a fungus and is frequently found on Colorado Blue Spruce and Norway Spruce. White Spruce can also be affected and there are a few reports of infected Serbian Spruce.
Initial symptoms include dying of lower branches with subsequent needle browning. The brown needles may remain on the branches or they may fall off. As the disease progresses over several years, higher branches show damage. The cankers may be seen on the infected branches. The bark of the cankered areas is not visibly different in color, however, resin flow is usually associated with Cytospora Canker and the white patches of dried resin are quite conspicuous on the bark. Cankers often cannot be located without cutting into the bark. Removal of the outer bark from the cankers reveals darkened, dead areas of the inner bark and cambium.
Cytospora Canker is more common in trees over 20 years old. The spores of the fungus are spread by splashing water, wind-driven rain, by pruning and also by birds and insects. It is prevalent in weakened trees; trees with shallow roots, weakened by drought, low fertility, mechanical injury or insect damage.
To help prevent infection, avoid bark or stem injuries, control insect problems and fertilize. Water trees during extended dry periods. Prune and remove or destroy affected branches. No effective chemical control measures are available and the trees usually succumb to the disease in 10 to 20 years.