This is just a brief introduction into cracks

Click here for SHIGO POINTS on CRACKS

Norway Maple

The crack at point A is extended from wounds at point B.  So the primary agent is the old wound as the starting point of the crack.








The white points are the crack which is a result of included bark.  The red pointer is where wetwood fluids are exiting.  Wetwood is a Protection Wood.  Here cables will be installed following some selective pruning to extend the safe period.  We will not drain wetwood because it is a protection feature for the tree.









Trees have a language.  We call it the body language of trees.  You learn to see the signs.  Here we have what we call Pinocchio Noses.  They are a sign that this tree may be moving into a high risk of hazard category.  Next picture will be a transverse view of this tree.







The Green Pointers is a primary crack.  The blue points to color altered wood from a wound or an injury.  That is not heartwood and this tree, beech, is not a heartwood forming tree. 









The green points to the barrier zone.  The barrier zone represents the size of the tree when it had a serious wound.  The Red Arrows are 3 cracks that are starting from the old wound.  Microorganisms are following the crack so you are starting to see the changes in color as a result.  Remember, the crack comes first then the microorganisms follow.  One point is that the cracks are not starting from sun or frost.  The starting points are old wounds.
Image Source - TREES, ASSOCIATES, and SHIGO (2 CD set).








Same theme here again. Over and over and over.

Image Source - TREES, ASSOCIATES, and SHIGO (2 CD set).









Here is a crack below an old branch stub.

Image Source - TREES, ASSOCIATES, and SHIGO (2 CD set).













Red Oak

This is not a crack starting from the inside out, this is at the base of a fissure as the tree is growing in girth.

Image Source - TREES, ASSOCIATES, and SHIGO (2 CD set).






For more on items on cracks see 
(SHIGO, 2002 and SHIGO, 1986)

Shigo CD's

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John A. Keslick, Jr.