Cytopsora canker

If you are seeing that the lower branches of your spruce tree are starting to die, then most likely this is due to Cytospora canker. Other diseases, including needlecast, commonly cause canopy breaching in spruce trees, but Cytospora canker is the most common cause. Cytospora is a fungal disease that is spread by windborne and waterborne spores. When the pathogen enters the cambium layer of a branch, it begins to form a canker, which is an infected area of wood that sheds a distinctive white resin or gummy sap. The resin or sap is the tree’s natural defense response to injury and is a useful diagnostic symptom. The canker continues to grow and eventually encircles the branch’s stem, thereby interrupting nutrient flow and killing it. Typically, the infection first occurs on older, lower branches, but not always: the needles on affected branches often become purple before browning and dying.

When cankers occur on the main trunk, the flow of water and nutrients is interrupted, and branches above the infection become gangrenous. Cytospora canker can occur on trees of any age, but it is most common in trees over 15 years old, and it usually occurs when the tree is stressed or has been stressed. Common urban stressors include drought, overwatering, winter damage, insect infestations, mechanical wounds (like those caused by lawnmowers), and construction damage. Of these stressors, drought is the most common trigger for Cytospora canker. There is no cure for Cytospora canker, so preventing it in the first place is critical. Your first line of defense is your spruce tree’s overall health and vitality.