Sparse leaf coverWe showed this image as an illustration for a Zone 1 inspection. It also falls into a Zone 4 inspection. Look at how sparse the leaf cover is in the crown of these trees.
Broken pine branchThis broken branch is easy to spot because of the differently-colored (dead) needles.
Cracked branchThis branch was loaded with mulberries. The weight of the fruit caused it to break.
Dead branch (with detail)The fungus on this dead branch over the street tells us that the branch can break at any time.
Weak branch unionThis branch was decayed where it attaches to the tree. It should be removed before it hurts someone or something.
Widow makerA widow maker is a branch that is broken but hasn't fallen to the ground; it can come down at any time. We know this branch is broken because of the brown (dead) needles.
Zone 4: The crown
The crown includes the leaves and all the branches that extend out from the trunk.
One of the most common and obvious dangers in a tree's crown is dead wood. Dead branches are easy to spot in a hardwood tree. If the rest of the tree still has green leaves, the dead branches are the ones with brown leaves or no leaves at all. A pine branch that has recently died will have brown needles; if it's been dead for a long time, it won't have any needles.
Branches that have been dead for a while won’t have any bark on them. These dead branches break easily. They should be removed carefully so they don't fall on someone or something. A hardwood tree that has many brown leaves on it in winter is probably dead (except for American beech trees, which hold on to their dead leaves until early spring.)
Look for broken branches, especially after a strong storm. On some trees you may not know that a branch is broken until about a month later, when the leaves turn brown.
Pockets of decay or rot sometimes exist on the upper side of a branch, where they are invisible to a ground observer. A “aerial” tree inspection by a Certified Arborist in which he climbs the tree may be required. This is especially true when there are large branches that extend over the house.