Survival of four trees in Dublin square could hold key to reviving native Irish elm, expert says
South Dublin’s Kenilworth Square could hold the key to the future of the wych elm tree species in Ireland.
Tree expert Joe McConville identified four trees in the Victorian square in Rathmines, owned by the Congregation of the Holy Spirit, which he is almost certain are resistant to Dutch elm disease (DED).
Over the last 50 years, the disease has all but wiped out elm trees from Ireland, Europe and vast tracts of the planet, bar a few rare specimens which show a level of resistance.
These trees are of genetic importance because their offspring could hold the same tendency to resist the disease, fuelling hopes of a resurgence in this once-widespread species.
Mr McConville, a former president of the Tree Council of Ireland, made the discovery when he was approached by residents of Kenilworth Square to carry out a tree survey in mid-2024.
“The question I was asked at the beginning was whether or not the trees that were there on the square were contemporary with the building of the square. And I was able to confirm that they were,” the arboriculturist said.
“But in doing that, we came across a couple of strange anomalies, one of which being the group of the elm.”
I can’t think of another stand of live elms in Dublin any more
Mr McConville said nobody had noticed that the trees were elms, despite them being around 60 years old.
“You can look at a tree and go, ‘that looks like an elm, but it can’t be that big’, but when you see the fruit, the fruit is so distinctive,” he said.
“So that really took me aback, the joy. Because I can’t think of another stand of live elms in Dublin any more.”
There are several varieties of elm in Ireland, but wych elms are considered to be the only species native to our island, making the discovery even more important from a biodiversity perspective.
DED is spread by a bark beetle that burrows into the elm, carrying with it a fungus that is fatal to the tree.
“The tree responds by blocking up the vessels, this is called the vascular wilt,” Mr McConville said. “And then the canopy of the tree dies back, the baby beetles hatch and they fly. Now, this is the important bit, the beetles only fly for 5km.”
Some elm trees have been protected in the past from the beetles by mass felling in a radius around them, he said, but this can only hold the beetles off for so long.
You could identify a live elm and then come back the next year and it’s infected
Mr McConville’s rule of thumb when he comes across potentially resistant elms is to monitor them for a few years, because “you could identify a live elm and then come back the next year and it’s infected”.
He added: “I’ve had those [Kenilworth Square] trees on my radar for two summers and normally, if I had three springs and three summers, then that’s when I would be happy that these are not just a fluke, they’re resistant.”
Further bolstering claims of resistance is that another set of dead elm trees are located in the square, having long-since succumbed to DED.
This indicates that bark beetles carrying the fungus definitely made it this far, but the four wych elms on the western edge were not affected.
Only a handful of cases of resistant wych elms have been found in Ireland, with semi-state body Teagasc logging only one resistant tree near An Spidéal in Co Galway. Other organisations, such as the Native Woodland Trust, are also seeking elms displaying resistance.
The environmental charity is encouraging the public to embark on a “wych hunt”, in the hopes of finding mature specimens that could herald the revitalisation of the species in Ireland.
They are certainly tall enough to have attracted the attention of bark beetles
After examining the Rathmines elms, Jim Lawlor of the trust confirmed the trees in Kenilworth Square “show positive signs of elm disease resistance and are probably a valuable genetic resource”.
“They are certainly tall enough to have attracted the attention of bark beetles – as have trees in such places as St Stephen’s Green, Bushy Park and housing around Terenure – growing in a city park is no protection,” he wrote.
Mr Lawlor will visit again in May or June when the tree’s foliage is visible, making it much easier to identify and examine.
The trees along Kenilworth Square are currently the subject of a tree preservation order bid by Green Party councillor Carolyn Moore to make sure they are protected for future generations, a move which Mr McConville said makes sense.
“The joy of a preservation order is… the management of that tree then becomes integral with the planning authority, the city council and the local residents,” he said. “Whereas if a tree just remains on private property, its management is basically up to the owner of the land, whether they’re informed or not.
“If you get an owner that has no understanding and maybe looks at a book and says, ‘oh that’s an elm, they’re going to get disease’ and then cuts them down, there’s no check or balance.”
Dublin City Council has not confirmed whether it will enact a tree preservation order for the square, but told Ms Moore its parks department would be carrying out a report.