To identify diseases in maple trees, examine the bark for cankers and lesions, check for signs of girdling roots and analyze the tree to see if verticillium wilt is present. The difficulty of the identification process depends on numerous factors, including the visibility of the symptoms.
- Check for cankers on the bark
The most common maple tree diseases come from fungus that causes cankers on the bark. Pink and black lesions are a sign of nectria cinnabarina. Nectria galligena can be identified by bark that looks like split and peeled paper. Eutypella looks similar to nectria galligena; however, it is thicker and more difficult to peel. Valsa cankers look like white or gray warts and grow in shallow recessions on young trees and branches. Steganosporium cankers look like a brittle, black layer covering previously diseased bark. Young maple trees may be affected by cryptosporiopsis cankers, which look as if the bark has been forcefully pushed into the trunk. Bleeding bark looks wet and may also peel. Rotting wood and bark at the base of the tree is often a sign of basal cankers.
- Look for girdling on the roots
Girdling roots are twisted and not able to deliver water and nutrients to the tree. Signs of girdling include a decrease in leaf size and brown borders surrounding the leaves. The limbs may also die completely.
- Check for signs of verticillium wilt
Verticillium wilt occurs when fungus enters the root system. Signs of verticillium wilt include fading yellow, brown or green leaves and wilting branches. This often occurs on one side of the tree.