Cut off and destroy infected twigs. No chemical control is listed. Several rusts attack firs but are not a problem on landscape trees. Since the diseases are rarely seen, control measures are not given. Several different fungi cause cankers on the trunks and branches of firs.
Cankers are sunken areas in the bark that gradually get larger.
When the stem is completely encircled the part beyond the canker dies. There is no chemical control for canker diseases. Keep the plants healthy by fertilizing and watering during dry weather. Cankers can be prevented by avoiding plant injury. Root rots caused by several fungi kill roots and rot wood.