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What is Summer Branch Drop (aka. Summer Limb Drop, Sudden Limb Drop) and what can I do to prevent it?

Posted on Tuesday, September 6, 2016

Summer Branch Drop (SBD) is a little understood phenomenon that is gaining some local attention as of late after a recent tragic incident in Trinity Bellwoods Park, Toronto. SBD has been reported in Australia, Europe and the US since the early 1970’s. In these incidents, limbs fall for no apparent reason on calm, hot summer days.


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It has been suggested that the limbs may fall due to a buildup of water pressure inside the limbs, or possibly because of the release of certain hormones that weaken cell walls within the branch, but it is largely unstudied because it is extremely unpredictable and therefore difficult to replicate in scientific experiments.


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Since it is so understudied, there are no current suggestions to prevent SBD, but there are some recommendations to reduce the chances of a tragic limb drop on your property:


- Reduce the length and weight of large limbs, especially those over houses, paths, driveways or recreational areas

- Thin the canopy to promote the movement of air and lessen humidity

- Remove dead, dying or diseased branches (those with cankers, cracks or other rotting areas)

- Remove trees that are of low vigor (for example, large or many areas of decay) in high-traffic areas


Services that we offer:


Here are some services that may help you with your hazardous trees this season!


- Pruning

- Tree Fertilization

- Tree Removal




Summer Branch Drop

Summer Branch Drop by Richard W. Harris  Presented at the 58th Annual Conference of the International Society of Arboriculture in Louisville, Kentucky on Aug 10, Journal of Arboriculture 9(4): April 1983