What is Sudden Drop Syndrome? Why Do Some Trees Lose Their Branches in the Middle of the Summer?

Summer branch drop is when a heavy limb falls unexpectedly, this tends to occur in the afternoon on hot, calm days. Older, less vigorous trees seem to be more prone to this problem. As well as sycamore, oak, elm, eucalyptus, etc. Once a tree has lost a limb due to summer branch drop, it is more likely to lose another.

An example of a tree cracking

Symptoms of Sudden Drop Syndrome

  • Large diameter limbs will break 3 to 12 feet from the trunk

  • Cracking or popping sounds just before large tree limbs plummet

Factors that the condition is attributed to

  • Drought-weakened cellular structure - in summer, the increased temperature, lack of moisture, and weight of the leaves on the tree can cause branches to fall and drop

  • Evapotranspiration (sometimes called transpiration) - describe the process involved with trees “sweating”

  • Infection - decaying tree limbs are an open door for infection which could weaken the structure of it and eventually cause it to fall off

  • Pre-existing limb defects - although this is not normally associated with sudden limb drop syndrome, any defect that is neglected or overlooked could worsen over time and result in the dropping of limbs

How to prevent this occurrence

Because sudden drop syndrome does not have a definite cause, there is no direct way to prevent it. However, there are a number of ways that you can protect your tree and reduce the risk of it happening.

  1. Properly exposed trunk flares (also known as root flares).

  2. Quality pruning done by a certified Arborist will ensure that flush cuts and excessive thinning is avoided.

  3. Regular plant health care practices (organic fertilization, soil aeration, etc.)

  4. Proper watering, avoid overwatering. Remember, it is better to water less often for long durations to help promote deep healthy root systems


Contact Arbortech Tree Care Inc. (510) 881-8733, your tree care experts, if you experience sudden drop syndrome or if you experience any other issues for which you might need tree pruning or other tree care services.


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