Anthracnose

Anthracnose

Anthracnose is one of the most prominent unsightly diseases of shade trees.  It is a foliar disease caused by different species of fungi.  The disease is most active in the spring and can become quite severe if cooler wet weather persists in spring.   as Due to the progression of the disease into stem and bud tissue, some trees like sycamore and dogwood are more inclined to be adversely affected by anthracnose.

Affected trees: ash, oak, dogwood, elm, hickory, walnut, maple, and sycamore. 

 

Noticeable Signs

Common signs of anthracnose tend to show:

  • tan to brown or black blotchy areas along the leaf veins.
  • infected areas will expand outwards towards the leaf margin, causing irregular brown patches that distort the leaf.
  • Tiny fungal spore masses can be seen on the underside of infected leaves through a magnified lens.
  • Compromised leaves are more noticeable on lower branches.
  • Younger leaves may die and fall after initial infection, but re-leaf by summer.
  • Cankers can be seen on stems and branches of severely infected hosts.

Treatment/ Management

Anthracnose can be managed through proper ground sanitation of leaves and branches in the fall. Pruning cankers (localized injuries) from infected stems and branches back to healthy laterals can stop or slow the progression of the disease.

Depending on severity of the Anthracnose, along with the cultural practices described above, we would recommend a 3-application foliar Fungicidal spray program beginning in the spring when the buds first appear along with two additional sprays at 10-14 day intervals.