Spruce trees are susceptible to few diseases, but the ones they are prone to cause the trees to lose needles, branches or both. The resulting aesthetic problems create issues for tree farmers. While the diseases themselves are not always fatal to the tree, often the only cure is removal of the infected branches or removal of the entire tree before the infection can spread to surrounding trees.
Caused by the fungus Rhizosphaera Kalkhoffii, this disease causes the tree to lose its needles too soon. Normal spruce trees hold their needles for up to 7 years, but an infected tree loses its needles each season. This fungus infects the lowest branches first and gradually works its way up the tree. Sometimes, the lower branches die but the rest of the tree remains alive.
Cooley Spruce Gall
This brown, woody growth resembles cones protruding from the ends of the spruce branches. These are unattractive at low infestations and destructive in greater numbers. They cause the tips of the branches to be choked off from the rest of the branch, which kills the branch tip. This ensures that new growth doesn't happen on the affected branch.
Easter Spruce Gall
These galls look like pineapples and choke off new growths on spruce branches. Some trees are more susceptible to the condition and develop huge galls all over the tree. The more galls there are, the less chance of the tree's survival. Just a few of these galls will not disturb the growth cycles of the tree.
Salt thrown down during the winter or strong chemicals, such as herbicides, cause the branches at the bottom of the tree to die. Then the rest of the branches die out in a pattern that spirals up the tree. The disease is characterized by this odd patterning of living and dead branches.
Cankers form on the branches as a result of a fungal infection, usually at an injury point on a branch. These infections cut off circulation of nutrients to the infected limbs of the tree. The result is death of the infected branch. The only cure is to remove the dead branches before the canker can spread further.