Cytospora Canker

Scientific Name: Cytospora kunzei var. piceae

Cytospora cankers will infect many tree species, however the most common Cytospora in Minnesota primarily infects Colorado Blue Spruce. In its native habitat the disease is not an issue, but in locations where high humidity occurs, it is a very destructive disease that can kill mature Colorado spruce. Most trees are infected and begin to show symptoms after they are established (>15 years). The most effective management is to reduce environmental conditions that stress the tree and to reduce the moisture conditions that increase the spread of the disease.

Attacks: Colorado blue spruce, Norway spruce, Douglas fir, hemlock and balsam fir

What you will see:

• Affects low branches and progresses upward
• Cankers form at the base of small, infected branches
  • Elliptical
  • Diamond-shaped
• Bluish white pitch covers the cankered area
• Spores are produced in the cankered area of the bark

Life cycle:

• Infects old trees and young trees in poor environments
• Moisture induces spore formation
  • Orange-colored tendrils of spores
  • Spread by splashing rain and wind
• Infection takes place most frequently during spring and fall
• Spores infect wounds or other weakened tissues

Cultural Management of Cytospora Canker

Cultural practices:

• Avoid bark and stem injuries
• Control insects and mites
• Prune affected branches in fall or early spring
  • Sterilize pruning tools between cuts
• Enhance vigor
  • Reduce stress in environment by reducing or enhancing watering
  • Increase tree vigor with
    • Tree nutrition
    • Prescription Mulch©
    • The Root Enhancement System©

Chemical control options are not available