Two 100-year-old white birch trees next to are sick and could die within 10 years without intervention.
Both trees, which are each about 65 feet tall, each have a disease known as phytophthora canker and are infected by bronze birch borer, according to Tree Warden Pierre Erhard.
“I think these birch trees are the most valuable trees in this town because of where they are,” Erhard said.
The heart of the problem is with the grass and compacted soil that surrounds the trees. The trees’ root hairs need oxygen and water, according to Erhard, and the turf restricts that. In addition, the compacted soil further reduces the ability of oxygen and water to get to the roots and as the trees get older the trees also get more vulnerable and the immune system is compromised.
Erhard has a suggested treatment – perform a process known as root collar excavation, which is essentially pulling up the grass and compacted soil around both trees. It should be done as far out as the tree’s canopy stretches, but Erhard said it could stretch about 15 feet from the tree trunk and be effective.
From there an “air spade” would be used to blow dirt away from the roots without causing injury and then the area would be filled in with compost and topped with bark mulch.
It would leave a “figure eight” surrounding the trees, Erhard said, and be much more like the forest floor where the trees typically grow.
The total cost of the work would be about $1,500, Erhard said. The annual tree warden budget is $20,000.
Some town officials he has spoken with are opposed to the work because it will remove some of the grass alongside the Town Hall. Because of those concerns, Erhard has plans to explain the situation to the Board of Selectmen at its next meeting.
And the trees cannot just be treated alone, Erhard said. While the insects will require ingoing treatment, the “root collar” is needed in addition, Erhard said, to ensure that the trees survive.
Otherwise, he said the trees have a 5-10 year lifespan.
“Treating the disease (without the root collar) would be like banging your head against the wall and taking aspirin for a headache,” he said.
Signs of the trees’ sickness include leaves at the top becoming lighter green than those at the bottom, showing a lack of nutrients reaching the top of the tree.
“The whole tip of the crown looks weak,” Erhard said, while standing under the trees and looking up on Monday afternoon.
In addition to Erhard’s diagnosis and suggested treatment, Erhard said Ben Staples, a board certified master arborist, has come to a similar conclusion.
While the health of the tree has been in decline for years, Erhard said he has been spending the past few years working on addressing removing hazardous trees along town roads. Several weeks ago he recently made the diagnosis and started coming up with a way to save the trees.
“If we do not do this treatment these trees will die within 10 years,” Erhard said.