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​Common Tree Diseases in Wisconsin

Signs & Symptoms of Tree Diseases in Wisconsin

Our Certified Arborists believe that early disease detection can be an important part of protecting your trees. By providing our gallery of tree diseases common in Wisconsin as a resource for our clients, we hope to help your trees as soon as the signs of damaging diseases appear. While this tree disease gallery is a useful resource for beginning the process of accurate tree care, it is important to have your tree diagnosed by a tree care professional. Contact our Certified Arborists if you suspect that your trees are being affected by one of these common tree diseases below and we will start a custom plant health care plan for your property.

a leaf infected with apple scab

Apple Scab

  • Fungal disease of ornamental crabapple and apple trees
  • Leaves will develop small brown to olive green spots
  • Most common in spring and early summer


  • Fungicide treatment 2-3 times per year
  • Annual treatment is necessary

More About Apple Scab

Tree Fungus Treatment


  • Fungi that affects Pines and Spruces
  • Browning can develop slowly, over several years, or rapidly, depending on spring weather conditions
  • Fungi attacks needles as they emerge and is especially affective with moisture from rains or heavy dews


  • Can be controlled through a protective fungicide spray program
  • Spray treatment protects the new growth that arrives in spring; it can take a least 3 consecutive years of treatment to have aesthetic beauty return

More About Needle Cast

Dutch Elm Disease

  • Fungus that is transmitted from one Elm to another
  • Symptoms typically arise in late spring or early summer
  • Leaves on outer branches will curl (wilt) turn gray-green or yellow and then brown


  • Trunk injection
  • Sanitation pruning of recently infected branches may help

More About Dutch Elm Disease

tar spot

Tar Spot

  • Black spots on maple leaves
  • Will not kill your tree, just a cosmetic issue
  • Easily spread from tree to tree each year

More About Tar Spot



  • Caused by fungi infecting newly emerging leaves in spring
  • This disease will not result in the death of your tree
  • Systemic fungicides can be used to combat the disease

More About Anthracnose

oak wilt

Oak Wilt Disease

  • Dull green/bronze leaves
  • Careful to not injure/trim Oak trees from April – July as that is the most common time of infection from the spore-carrying beetles.
  • Remedies must be acted upon quickly in order to save the oak trees.

More About Oak Wilt