Written by: Robert Smith for The Arbor Day Foundation

Q:  I’ve noticed that sometimes trees drop their twigs and leaves in the summer.  Is this normal for certain species or is this an indication of a problem?

The terms for what you are seeing are “summer dormancy,” “summer leaf drop,” and “cladoptosis,” the latter meaning “a branch” and “falling.”  By whatever name, what you see is a reaction to stress.  

This may be due to planting a sun-loving species in the shade or vice versa, or it might be a reaction to soil compaction.  Saturated soil can also be a cause.  More often, however, it is simply due to heat and drought.  In this case, the dropping of branches and early shedding of leaves is temporary and harmless.  Winter and adequate water should restore the tree to more normal conditions.  You might see this in just about any species, but those that seem to do it most commonly are birch trees, maples trees, willow trees, hackberry trees, and western redcedar and its relatives.  

The lesson here is:  plant the best tree right tree in the right place and, when possible, provide adequate tree watering during prolonged dry periods.

Source: R. Smith (2010, August 19). Summer Tree Care. Retrieved from http://arbordayblog.org/treecare/summer_tree_care