Limbs can fail due to heavy and unnecessary loads of foliage or genetic defect, but there is another cause happening all around the Bay Area. It is called “sudden limb drop phenomena,” or sometimes referred to as “sudden branch drop.”
The phenomena causes limbs to break commonly on hot and windless days, with no obvious external signs of defect or trauma to the tree. The inner wood is broken bluntly (round and flat breakage), as opposed a breakage with sharp splintering.
Arborists studying sudden limb drop, or sudden branch drop, have found no consistent causes or visible warning signs. Some arborists theorize that sudden branch drop may be caused by change in branch movement, moisture changes, ethylene gas released inside the branches, however there are still no definitive answers.
So what can you do about it? First understand which trees commonly suffer from sudden limb drop. They include, but not limited to:
- Eucalyptus Quercus
- Ulmus Procera
- Fagus Sylvatica
Next, reduce the risk. Trees are living organisms and even a qualified arborists will not always detect when, and which limbs may fall. But we can take measures to prevent sudden limb drop.
1) Prune at risk tree limbs for crown thinning.
2) Install a cable system to limit motion and share the load with other limbs or nearby trees.
3) Request an Arbortek Arborist to visit your property to identify at-risk trees.