Four trees believed to be more than 130 years old sit south of the Octagon carriage-way and are distinctly bare compared to their leafy counterparts.
In 2010, the Dunedin City Council spent $50,000 to rehabilitate the trees, after fears they were under attack from a mysterious fungal infection.
The Ministry of Agriculture and Forestry investigated and found no sign of primary pathogens, but said the trees appeared susceptible to secondary pathogens, a weakness that could be due to their urban environment.
In 2015 two trees were removed.
Asked about their condition this week, a Dunedin City Council spokeswoman said "various strategies" had been tried over recent years to improve the health of the trees.
The council would continue to monitor the condition of the Octagon trees, of which four are still considered vulnerable.
"We have no plans to remove them," she said.
She said fresh soil samples had been taken from the surrounding area, which were awaiting laboratory analysis.
When the results were received, council would look to improve the conditions of the area.
"Some dead wood will be removed early next year, but other wood that appears dead is merely dormant and will be retained for now," she said.
