Fungal Infection Caused Ho Man Tin Tree Collapse, Probe Finds

A fungal infection caused the collapse of a tree in Ho Man Tin last month in an incident that injured at least two people, according to an investigation by the Development Bureau.

On Sept. 16, a large Delonix regia tree, colloquially known as “flame tree,” was suddenly uprooted, collapsing on four vehicles and injuring one school bus driver and another private car driver.

In response to this incident, the Leisure & Cultural Services Department (LCSD) investigated to understand why the tree collapsed, and to mitigate the risks of a similar accident in the future.

Through on-site inspection, collection and testing of samples, and tree records, the LCSD concluded that a fungal infection caused the flame tree's collapse. This was further attributed to the tree’s phototropic response, close paving blocks, and white rot fungus.

As the tree orients itself towards a light source, the centre of gravity shifts away from the root zone. Due to close paving blocks, the roots were not able to extend properly and uphold the infected trunk which weakened the tree.

Upon the Tree Management Office’s (TMO) request, the LCSD inspected 34 trees in the area and has since removed white rot fungus from infected trees.

Currently, there are more than 10,000 flame trees on Hong Kong roadsides, with the TMO requesting the relevant departments to re-inspect more than 4,000 of them. At least 59 flame trees will be removed around November.

More investigations concerning roadside trees are expected to be finalised in the same month.