Author: Matt Copley

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Hypoxylon Canker

Tip Die-back Oak with hypoxylon canker (Photo by J. Pase) Bark sloughing off

Hypoxylon Canker is a fungus, common in the Southeastern United States, caused by Biscogniauxia atropunctata var. atropunctata.  Hypoxylon Canker, also known as “white rot”,  most commonly affects: oaks, pecans, and hickory trees. This opportunistic pathogen easily infects trees that have gone through stresses such as: drought, compaction, root injury, construction, trenching, grade changes, and root diseases.  Hypoxylon canker is a vascular disease, meaning it affects a tree’s “plumbing system.”  The tissues (xylem) that conduct water from the soil to the leaves are damaged by the fungus. Basically anything that will cause the moisture levels of the tree to decrease will cause the fungus to become more active.  Some trees that are healthy and have adequate moisture content can defend themselves against infection.  This is a very fast and difficult disease for the tree to overcome.  Depending on the tree’s potential targets, it may be necessary to go ahead and remove the tree ASAP.

The first symptom of Hypoxylon Canker is a thinning crown.  Thinning crowns are common with many different  stresses to a tree.  Do some more investigating and take a look at the bark of the tree.  The bark will start to slough off and collect at the base of the tree.  Once the bark sloughs off it will reveal the brownish fungal stroma where the asexual conidia are formed. Conida are most often spread by wind/rain and can cause infections on other trees.  As the infection progresses the brownish spots will begin to turn a grayish/silver color and eventually black.  Once the infection turns black, this is where the sexual spores are produced.  These spores are mostly spread by splashing rain, wind, and insects.  While there is no control, the best thing to do is promote vigor in the tree by stimulating the root system with our patented process.

To avoid Hypoxylon Canker  from becoming a significant problem in your trees:

  1. Increase the overall health and vigor of  your trees with regular and ongoing deep root fertilization.  More aggressive programs may be required to help rehabilitate stressed or damaged trees.
  2. Regularly check your trees for any weak, damaged, or dead limbs.  If present, pruning may be necessary.
  3. Avoid any injury to the trunk and limbs of a tree.  By reducing injuries, the trees are healthier and the chances of infection are reduced.
  4. Avoid grade changes around a trees root system.  This will cause root injury and decline in the tree.
  5. Use extreme caution when disturbing the  environment of any existing tree.  A tree becomes much more likely to develop a problem the older and larger it gets.  A mature tree is much less resilient to even minor changes in its environment than a younger tree.  This includes any activities such as trenching, compaction, construction, and grade change.

Fulgham’s Inc. provides free consultations.  If you would like us to take a look at your trees please give us a call at 1-800-316-3360.

– Matt Copley



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