Anthracnose

Scientific Name: Apiognomonia spp.

Anthracnose is a fungal disease that infects ash, oak, maple, and sycamore trees growing in Minnesota. The fungus causes dead blotches on the leaves that disrupts photosynthesis and transpiration which can eventually lead to spring leaf drop. As leaves mature they become less susceptible to the pathogen. Repeat defoliation by anthracnose can reduce tree health.

Attacks: Ash, Oak, Maple, Sycamore

What you will see:

• Large tannish blotches and leaf distortion
• Distinct spots to irregular patches of discoloration
• Leaf blotches along leaf veins
• Shoot blight, leaf blight and twig and branch cankers
• Spring leaf drop

Life cycle:

• In late Fall and early Spring, black pimples develop on infected leaves from the previous year
• Spores are released and blown by wind or splashed by rain to nearby trees
• The fungus may infect leaves, fruit, petioles, and blossoms
• Primary infections produce secondary spores which infect other leaves and fruit
• Secondary infections continue throughout the growing season during wet periods

Cultural Managements for Anthracnose

Cultural practices:

• Plant less susceptible cultivars
• Increase tree vigor
  • Root Enhancement System™
  • Fertilization
• Prune out infected branches (sycamore)
• Reduce moisture from sprinklers

Chemical Practices

• Fungicides are available to manage this disease. Please
  consult with your Arborist.