Octagon Trees Not At Death's Door

A report received by the Dunedin City Council’s Community and Recreation Services from the Ministry of Agriculture and Fisheries, indicate that the unhealthy plane trees in the Octagon show the presence of no primary pathogens and they are not, in fact, dead or dying. However, the trees appear to be susceptible to secondary pathogens, a weakness that may be due to their environment.

The report continues with suggestions for improving the health of the affected trees. While trees can heal and defend themselves against pathogens in an ideal environment, when planted in an urban situation, they need the soil environment to be actively maintained.

Suggestions in the report for future health of Dunedin’s street trees are based on three stages:

• Physical modifications such as removing surface plantings
• A change in maintenance practice - for example gentle or no pruning until they recover
• Therapeutic treatments such as addition of nutrients to the soil

The programme of work is yet to be finalised but will be non-chemical as there are no primary pathogens to kill.

DCC Community & Recreation Services Manager, Mick Reece, says, “This is good news albeit a bit of a wake up call for us. We now need to work out how to respond appropriately to achieve longevity for our city’s street trees while also considering the forward planning implications for having suitable replacement trees ready for planting in key areas and maybe with more urgency than previously anticipated.”

Mr Reece also commented that future urban design will have to investigate either which are the most suitable type of trees to be planted in these areas or, whether in fact trees are suitable for the Octagon at all. “We may also get to the situation where we are nursing some of these older affected trees for several years and they don’t improve and it may still be necessary to cut off the life support system.”