Defects during growth phase of trees

Defects that occur while the tree is growing (from natural forces and growth faults) are:

1. Shakes: cracks that separate the fibres along the grain, of several types:
   • Heart shake: radial cracks starting from the pith, found in over-mature trees.
   • Star shake: several radial cracks running from the bark inward, caused by frost or the sun's heat.
   • Cup shake (ring shake): curved cracks along the annual rings that separate one ring from another.
   • Radial shake: fine radial cracks from the circumference.
2. Knots: the bases of branches embedded in the trunk (live or dead, pin, spike); they disturb the grain and reduce strength.
3. Rind galls: curved swellings where a branch was cut off and the bark grew over it.
4. Burls (excrescences): abnormal growths on the trunk surface.
5. Upsets (rupture): fibres crushed by strong wind or by bad felling.
6. Wind cracks and twisted fibres (spirality): due to wind, and spiral growth.
7. Water stain, foxiness and callus: water stain is discolouration from contact with water; foxiness is a red or yellow tinge caused by over-maturity or poor ventilation; callus is soft tissue that covers a wound.