The graceful eucalyptus or gum tree is an Australian icon that adorns many gardens and backyards across the continent.   Although eucalyptus trees are pretty hardy, they can sometimes become prone to dropping branches, posing danger to both property and people.  But what causes this phenomenon and how can your local tree specialist help?

Disease

The usual cause of branch drop in eucalyptus trees is disease.  Look carefully at your tree.  If its leaves appear wilted or discoloured and are falling from the tree, an advanced form of rot disease may have set in. 

Phytophthora fungi are usually responsible for causing infection in the crown and roots of an affected tree, leading to rotting.  Vertical streaks of discolouration in the bark of the tree may also be seen together with leaking, dark sap.  As the disease progresses, the tree's branches will begin to drop and the tree will eventually die. 

The best way to combat a rot disease is to contact a tree specialist and arrange to have the diseased and dying branches removed.  By cutting out the fungus that causes the rot by removing the branches on which it is living, your tree will have a reasonable chance of survival.

Damage

As trees grow and age, they can become damaged by weathering or other environmental factors.  The following signs could indicate that your tree may drop one or more of its branches:

• If the tree's main trunk has multiple 'leaders' or new branches growing from it, the trunk may actually be split, predisposing the tree to dropping branches or falling altogether.  
• If the ground around the tree has subsided due to heavy rain or drought, the tree may begin to lean and become unstable.  
• If the tree has branch attachments that are 'V' shaped, rather than 'U' shaped, the branches will be more liable to storm damage and consequent dropping.  
• Look out for cracks or splits in the tree's trunk near to large branches.  This weakness could predispose the branch to falling.

Drought

Another cause of falling branches from an otherwise healthy tree is dehydration caused by an extended period of drought.  This is the tree's natural defence against severe dehydration as it seeks to retain moisture in its roots and leaves.  If possible, water your tree beneath the canopy, close to the trunk in order to hydrate the roots.  Always water your trees early in the morning or late in the evening to prevent evaporation by the sun.

In conclusion

You should have all your mature trees checked and pruned annually by a tree specialist to keep them healthy and in a good, safe condition.  Carry out a regular inspection of your eucalyptus trees and contact a local tree specialist if you observe any of the signs outlined above.  Prompt action could save your trees and your property from damage.