Why Are Lower Branches On My Spruce Tree Dying?

Cytospora canker of spruce

A common malady of blue spruce trees in southeast Michigan is a tree disease called Cytospora canker. Trees 20 years of age or older tend to be affected the most. Needles on lower branches will often become yellow, then brown. Often, needles will fall off the tree while still green. After several weeks, infected lower branches will appear defoliated and dead. Usually a bluish-white resin will be observed on branches near the trunk. The presence of bluish-white resin usually indicates cankers beneath the resin.

Bluish-white resin shows canker site on spruce branch infected with Cytospora canker. Photo: Joseph OBrien, USDA Forest Service, Bugwood.org

How to control Cytospora canker

At this point in time there are no documented fungicides available to control Cytospora canker. Control is primarily achieved through proper cultural practices.

Avoid tree stress by proper watering during mid-summer. This is best accomplished by coiling a soaker hose under and around the canopy of the tree. For even a moderate size tree let the hose run for two or three hours. This only needs to be done every two or three weeks during the driest part of the summer – usually mid-June to early September.

Mulching under your spruce trees will help conserve soil moisture during the hotter summer months. A mulch layer of two or three inches is adequate. Do not pile mulch against the trunk of the tree. The wounding of lower branches by mowers can encourage infection, so mulch rings should be extended to beyond the drip line of the tree.

Deep-root fertilization can help reduce tree stress by making sure there are nutrients in the soil when the tree needs them. Deep-root fertilization of spruce trees can be done in the spring or fall.

Branches with resinous cankers will eventually need to be removed. Sterilizing pruning tools between each cut will prevent spreading the disease within the tree or to other spruce trees in your landscape.

If you are seeing dead or dying branches on your spruce tree call Owen Tree & Lawn Care to have the trees checked and to develop an action plan to fight against this tree disease.

Lower branches of blue spruce dying from Cytospora canker. Photo: Joseph OBrien, USDA Forest Service, Bugwood.org