A 15-year study into Dutch elm disease in Fredericton found half of the local trees tested showed at least some tolerance to the disease.

Grafts were from cuttings from local elms 15 years ago and they produced 150 trees. Those trees were later inoculated with spores from the disease to see if any of them survived.

Half of the grafts that were injected with Dutch elm disease spores suffered heavy damage, while a quarter of them were somewhat damaged and the other quarter showed little ill effects.

Dale Simpson, manager of the National Tree Seed Centre, said the grafts that sustained heavy damage will be removed and the others will be monitored.

“Both those groups will stay and probably over time, maybe if disease symptoms show up on them, they will in turnover be removed,” said Simpson.

Even if only a quarter of the grafts showed no sign of damage the result is promising, especially considering that the disease isn’t native to the area, he said.

“These trees would have no natural immunity against the disease. It’s really a freak of nature that some trees have possessed the ability to fend off the disease,” said Simpson.

Once well known as the City of Stately Elms, Fredericton saw a dramatic decrease in its population of elm’s after Dutch elm disease was first spotted in the city in 1961. By 1990 more than 13,000 trees were lost.

Simpson hopes the work done in the study will help the city’s elm population rebound.

“Hopefully maternal and offspring from those trees will be used to plant in Fredericton,” said Simpson.