Figure 8.  A black cherry one year after a pruning cut that removed the branch collar.  Flush cuts not only cause internal defects. such as discolored wood, decayed wood, and cracks.  They also reduce the volume of wood that can store energy reserves.  The healthy sapwood at left can store much more energy that the thin strip of sapwood at right.  When sudden cold or heat occurs, frost crack or sun scald can injure the thin strip of sapwood, which may crack or die.