Crown Defoliation  Crown defoliation is one of the main indices monitored for tree condition of both forest and urban trees. It usually indicates serious problems with trees of either a physiological or pathological nature. Defoliation is the term used to describe a situation where part of the leaf mass is missing and bare branches and twigs remain. Dieback (death of shoot and branches, generally from the tip to base) falls into this category as well. Bare twigs or dead branches in the inner crown are not considered crown defoliation. Similarly if a large tree has one or two small branches without leaves it is considered to be healthy. Three classes of crown defoliation are identified using the following rating: 0 Tree crown not defoliated (healthy).  Allow for minor twig defoliation, which is normal in a healthy tree. 1 Between trace amounts of defoliation and less than 1/4 of the crown having lost its leaves - crown slightly defoliated. 2 1/4 to 1/2 of the crown had lost its leaves - crown moderately defoliated. 3 More than 1/2 of the crown without leaves - crown severely defoliated. Tree ProblemsDead or Broken Branches