Tree that fell and killed woman at Marsiling Park had termite infestation but no external signs, coroner's inquiry hears

SINGAPORE — A 20m-tall tree that fell and killed a 38-year-old woman last year showed no external signs of a termite infestation that came to light only after the incident, a senior National Parks Board (NParks) official told a coroner's court on Thursday (Oct 13).

Only three other trees across the island have fallen in the past 12 years due to termite infestation, and there are typically signs that allow the authorities to intervene in a timely manner, the official added.

Records from regular inspections also showed the coniferous tree to be in a healthy condition with no decay or cavities.

The authorities found the internal termite infestation when the tree was examined after the tragedy.

These new details emerged during the first day of a coroner’s inquiry into the death of Dag Loke Xiao Li.

Dag Loke, a senior technical coordinator with Mediacorp news channel CNA, had been exercising at Marsiling Park on Feb 18 last year when the tree measuring 1.3m in girth fell on her.

On Thursday, Mr Oh Cheow Sheng, the group director of NParks’ streetscape division, gave testimony on how the fallen tree was inspected and what the agency’s usual inspection regime is.

Mr Oh said that it was not practical or financially feasible to perform advanced-level inspections for all trees as a blanket first measure. Such inspections involve generally invasive techniques that can introduce pathogens into tree trunks, he added.

Three-dimensional models of a tree's external condition can also be constructed, but this is time-consuming and involves the use of complex equipment, he added.

He told the coroner’s court that the first level of assessment conducted by NParks is called a visual tree assessment. This involves the visual inspection of individual trees based on a comprehensive checklist.

An inspector examines the trees from ground level, looking at their crown, branches, trunk and above-ground roots.

Mr Oh said that this was more rigorous and stringent than the guidelines laid out by the International Society of Arboriculture (ISA), which are limited to looking for issues such as large cavity openings or dead branches.

NParks inspects trees every six to 24 months, increasing the frequency during adverse weather conditions, for example, Mr Oh added.

However, he said that NParks is now exploring alternatives for inspections and to “close technological gaps”. It is working with research institutes such as Nanyang Technological University to develop new diagnostic tools that could better detect internal issues.

"To date, there is no portable equipment that allows NParks to conduct rapid checks on trees to detect subterranean termite infestation," the official added.

A RELATIVELY YOUNG TREE

As for the tree that fell, Mr Oh said that it was a relatively young tree — 20 to 30 years old — with no special conditions.

The tree was an Araucaria araucana, native to parts of South America, and also known as a Chilean pine.

There are about 200 of these trees planted in Singapore and they are not known to be susceptible to termite infestation, Mr Oh added.

The tree was inspected once every two years before June 2019. However, NParks then began inspecting trees in public parks every 18 months due to more intense weather conditions such as heavier rainfall.

The tree was examined in October 2016, October 2018 and most recently in April 2020.

There were no signs of subterranean termites or any other kind of infestation, and the records consistently showed that it was in a healthy condition with no external signs of termite infestation, Mr Oh said.

Because of this, NParks did not conduct an advanced-level inspection on the tree.

After it fell on Dag Loke, NParks arborists (who takes care of trees) found that termites had entered the tree trunk from below the ground, mainly affecting the internal core at the base of the tree.

Water and nutrients were still being sent to the tree crown, which meant that its foliage did not show any signs of ill health.

NParks' employees then drenched the root zones of trees around the area with termiticide to prevent and destroy termite infestations. Mr Oh said that this was a precautionary measure due to the “publicity and heightened concern about tree incidents”.

No other trees in Marsiling Park were found to be infested on a visual assessment.

INFESTATION NOT COMMON

Mr Oh told the court that termites typically leave mud tracks on tree trunks. Termite mounds and faecal pellets can also sometimes be found beside trees, indicating their presence.

“At times, the tree may show an overall decline in tree health. All these signs and symptoms would allow a trained person to make that judgement call,” he added.

A lawyer for Dag Loke’s family, Mr Azri Imran Tan from IRB Law, asked Mr Oh how subterranean termites could leave external signs if they attacked only the inside of trees.

Mr Oh replied that a tree will show signs of stress if weakened, especially during hotter or drier weather.

"If for some reason, there is more rainfall in that period and the tree accumulates enough moisture, they will not show that kind of symptoms,” he added.

Mr Tan also asked if there are physical checks to identify termite infestation during visual inspections. Mr Oh said that to his knowledge, there is no simple way to detect this.

As for how common such termite infestations are, Mr Oh said that over the past 12 years, only three trees out of a “managed population of two million” have fallen because of it.

None of these were of the same species as the one that fell on Dag Loke.

The number of such tree failures has also dropped more than 80 per cent since 2000, from 3,000 cases then to about 300 to 400 cases now, Mr Oh added.

"We would say it is extremely uncommon, due to a combination of factors that happened where the tree was structurally compromised but did not show any external signs," the NParks official said.

The hearing will continue on Friday.