The Norway spruce, a medium-textured, evergreen, can reach heights up to 100 feet with a 35- to 40-foot spread. The Norway spruce slowly reduces its initial rapid growth rate as it ages. It develops persistent needles ranging from 1/2 to 1 inch long. It blossoms with pink terminal flowers, and its mature cones grow up to 6 feet in length. One of the most disease resistant of the evergreens, this European native even shows resistance against soil-borne diseases such as verticillium wilt.
This fungal disease, common among Norway spruce trees, attacks the tree through its trunk, causing cancerous sores on the trunk and base of the tree. Initial signs of infection include whitish colored patches and oozing near the infected area. As the infection continues, the point of infection will become hollow, dried and covered with a black fungal growth. Twigs and shoots will also experience dieback.
Cytospora cankers infect the tree when its wood is compromised during a dormancy period. Infections can be caused by winter injury, insect injury or pruning injuries. The fungus germinates during cooler temperatures and slows during warmer months. Fungal spores travel by wind and rain to the point of infection. Cytospora cankers can be controlled by removing the infected area from the tree. The infected cankers should be properly discarded to prevent cross contamination. Infected branches should be pruned from the tree.
This fungal disease travels via fungal spores, which lie dormant throughout the winter months. During the wet, warm spring months, the fungus infects the needles, both newly formed and mature ones. Infected needles turn brown with black fungal bodies on the underside of the needle. As the disease progresses, the infected needles drop from the tree. Infection can be fatal for the tree. Rhizosphaera needlecast can be prevented with fungicidal applications applied several times during the spring months. Control also involves the removal of the infected cankers. Gardeners should contact a horticultural or nursery specialist for assistance.
Spruce Needle Rust
As with needlecast, spruce needle rust, a fungal disease, infects young and mature needles. Infected needles will initially begin to yellow at the tips. As the disease progresses, the infected foliage will turn orange and develop white tubal extensions. These tubal extensions will begin to release an orange, powdery mildew and the branches of the infected foliage will begin to weaken. Though the infected tree is quite unsightly, damage is minimal. The diseased needles will fall from the tree towards the end of the growing season. Weakened branches should be pruned away. Control the disease by removing falling foliage and discarding appropriately to prevent continued infection. Keep trees dry and away from lawn sprinklers.