Cytospora canker is primarily associated with which host?

• A. Colorado blue spruce
• B. Red pine
• C. White ash
• D. Norway spruce

Answer: (A)

Cytospora canker is a fungal disease that shows a strong preference for certain woody hosts, and in ornamental settings the connection to spruces is the most pronounced. Among common landscape trees, Colorado blue spruce stands out as the classic host this pathogen infects. The fungus enters through wounds or bark cracks and forms cankers that can ooze resin and, under stress conditions, lead to needle browning and branch dieback. Because Colorado blue spruce is particularly susceptible—especially when the tree is stressed by drought, injury, or poor cultural conditions—the association is strongest with this species. Other trees can be affected in some cases, but they are not the typical or primary hosts linked to Cytospora canker in standard ornamental pest management.