Common Tree Pests and Tree Diseases in Colorado Everyone Should Know About

Trees are not only beautiful to look at, but they are also important to the environment. When tree pests or diseases strike, this can be a disaster—not only for the tree that has the infestation but for the rest of your trees as well as your neighbor’s trees. 

One of the main reasons why pests and diseases get the upper hand is often caused by environmental stresses that are created by humans. Things like weed whacker or lawnmower damage, salt from keeping areas free of ice, and construction can damage trees, leaving them vulnerable to attack from pests and diseases. 

In addition to treating trees carefully so they are not made unduly susceptible, homeowners should also be aware of common tree pests and tree diseases so they know what to look for. The sooner you treat a distressed tree, the better the chance of saving it. 

Common Diseases for Front Range Trees

Thousand cankers disease is a major problem along the Colorado Front Range and a relatively new disease that is spreading rapidly to black walnut trees. It is transported by the walnut twig beetle, which spreads a fungus that creates a canker around the tree. Signs of an infestation include branches that are browning around the tree crown. 

Other diseases include:
  • Anthracnose—a fungus that attacks leaves and twigs and overwinters in dead leaves and fallen branches
  • Bacterial wetwood also known as slime flux—causes liquid to ooze out of cracks or wounds in the tree
  • Cedar hawthorne rust—creates a reddish-brown rust ring on leaves/branches
  • Chlorosis—caused by lack of chlorophyll in plants because of too few nutrients in the soil
  • Cytospora canker—caused by fungus and is the main killer of the blue spruce
  • Decay—usually happens because bacteria gets into a wound on the tree
  • Dutch elm disease—spread by the elm bark beetle and causes leaves to wither and yellow
  • Dwarf mistletoe—caused by parasites 
  • Fireblight—a contagious bacterial disease
  • Leaf spots—usually caused by a fungus or bacteria that turns leaves.
  • Powdery mildew—caused by many species of fungi
  • Thyronectria canker—caused by a combination of fungus and drought
Common Critters That Endanger Trees

Beyond diseases, there are four main tree pests that love to destroy trees.
  1. IPS bark beetle—usually attacks trees that are stressed already
  2. Mountain pine beetle—can easily become an epidemic (This has already happened in the Colorado mountains. Thousands of trees have been destroyed by these pests. If you take a drive through forests in the high country, you’ll be able to see evidence of the devastation caused by these pests.)
  3. Emerald ash borer—a nonnative insect that got to Colorado in 2013
  4. Elm bark beetle—insects invade trees as well as homes
If you suspect tree pests or diseases in any of your trees, be sure to call the experts. Root Tree Service can help you manage these issues to protect the trees that are infested—as well as the other trees on your property. Contact us for strong, healthy, beautiful trees!
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