Common Diseases for Spruces

Rhizosphaera Needle Cast

• Rhizosphaera needle cast is a disease that affects the needles of a spruce tree. It is caused by the Rhizosphaera kalkhoffii fungus, which is often spread by dripping or splashing water in the spring and fall. The needles of affected trees usually turn yellow during the summer and become a purplish brown color in the winter or early spring. Lower needles are typically affected first, and the disease spreads up the tree. An infected spruce's needles fall off a year or so after it is first infected. In severe cases, the lower branches may actually begin to die after several years of infection. If the Rhizosphaera fungus is identified in a spruce, the tree may be treated with a fungicide over a two-year period to eliminate the disease.

Spruce Needle Rust

• Another common disease that affects the needles of a spruce tree is spruce needle rust. It is caused by several species of Chryosomyxa fungi, and is evident when the tree's needles begin to turn yellow. Eventually, white or orange tube-like structures grow on the needles and release spores. In severe cases of the disease, the needles turn a pink or tan color and eventually fall off the tree. However, spruce needle rust is mostly a superficial disease so the tree is not at serious risk. You can simply prune the diseased needles off the tree to improve its appearance.

Cytospora Canker

• Cytospora canker is a disease that affects the branches of a spruce tree. It is caused by the Leucostoma kunzei fungus, which usually targets trees that are weakened by various environmental issues, such as high temperatures, drought or frost damage. An affected branch's needles turn a purplish brown color and fall off. Several branches throughout the tree die, with the disease usually working from the lower portion of the tree upward. Infected branches may also show signs of a white, sticky sap that covers cankers. Cytospora canker typically infects spruce trees that are at least 10 years old, and while it does not usually kill the trees, it can distort their appearance enough that they are no longer appropriate for landscaping purposes.

Tomentosus Root Rot

• Tomentosus root rot is a disease that affects the roots of a spruce tree. It is the result of infection by the Inonotus tomentosus fungus, which is spread by spores. The heartwood of affected trunks and roots turns a reddish brown color until the wood decays and long, white pits develop. The tree is unable to get moisture and nutrients from the soil, so its growth slows and it is more prone to damage during storms. At some point, brown mushrooms may grow around the base of the tree as well. As the disease progresses, the tree eventually dies. However, the fungus can survive in the stump and roots of a dead tree for more than 30 years, so new trees can still be infected.