Jason and Aga Jones love the stunning oak tree that used to be the center of their backyard. In 2013 – a year after they bought their home in Takoma Park, Md. – they restored a circular wall that remained around the base of the tree. In 2019, they added an extension to the back of the house with large windows where they could admire the majestic branches and watch the squirrels build nests and collect acorns.
Then in late summer, when they hired a company to cut the branches that blocked the neighbor’s yard, the company workers pointed out the unpleasant symptoms: browning leaves, dead sanga. Within a year, the tree died.
“It’s sad. We bought the house because of this oak tree. It’s a beautiful old tree,” Jason Jones said, shaking his head as he stared at the brown leaves clinging to the lifeless branches last night before the workers to cut it. down.
He took a tape measure from his basement to look at the tree: 12 feet in circumference, 4 feet in diameter. “A couple of arborists told me it was probably one of the oldest trees in the state, but unfortunately it had blight and it had to fall,” he said, looking at his neighborhood’s wide green canopy. then back to himself. loud oak.
Oak trees are dying throughout the Mid-Atlantic region, crippled by extreme weather, old age, construction and development, and finally dying of disease and pests. Experts say the oak decline was triggered by a year of record rainfall that fell in the Washington region from 2018 to 2019, immediately followed by a flash drought in the hot, dry summer of 2019.
“The anaerobic conditions of flooded soil are not good for oaks,” said Karen Rane, director of the Plant Diagnostic Laboratory at the University of Maryland, noting that many of the hard-hit oaks are next to construction highway, where there are changes in drainage and soil compaction.
“They lose oxygen to the soil. That’s stress on older trees – or on any tree, but the older ones can’t tolerate it the way younger trees can. That could have triggered a acceleration of decline in older trees, ”Rane said. “When the trees weaken, the trees emit signals that allow opportunistic insects to find them and attack. That’s the last straw that cuts into the camel’s back.”
The oak decline has affected the Washington area and states including Pennsylvania, Virginia, Maryland, Delaware, West Virginia and New Jersey, experts said. Symptoms are early browning of leaves, thinning of the canopy cover and loss of branches, wrote Dorothy Borowy, an ecologist and coordinator of integrated pest management for the Washington region of the National Park Service, in an article last year. years.
Anne Arundel County in Maryland has even set up a web page where residents can report sick or dying trees.
The resulting tree loss is most evident in communities with older trees, such as Takoma Park, where residents are concerned because the roar of chain saws and mulching machines illustrates the loss of another large tree. of shade.
Takoma Park, a suburb known as a liberal enclave, has strict provisions to protect its trees. A permit is required for the removal of any tree, living or dead, with a trunk more than two feet in circumference, and for any construction, excavation or pruning that will remove more than 10 percent of the “live canopy . “
Marty Frye, the city’s forest manager, said that in the years he worked for Takoma Park, more than half of the tree removal permits he reviewed were for oak trees. He started his current job in October 2020 but began working on tree removal permits in the city about three years ago-where, he told colleagues and property owners, the increase began. of the death of the oak tree.
Rane, who traveled throughout the region to observe the oak tree situation, said of Takoma Park, “It just so happens that there are a lot of over-mature trees in that town.”
His U-Md. colleague Dave Clement, estimated that most dying trees in the region are between 80 and 120 years old.
“People think oaks live up to 300 years, but not in an urban environment. There’s a lot going on,” Rane added.
At Jones ’home, Jason Jones picked up pieces of bark that had fallen from the tree to reveal small piles of sawdust under the tree. These piles, Frye says, are a “predictable sign” of pests such as the Ambrosia beetle, which attack after the tree indicates its weakness.
Some trees are slowly dying, losing branches over many years, Frye says. But others, like the head of the Jones family, died suddenly.
“That’s a more confusing, surprising sight,” Frye said. “It looks like it came out well, then browned out pretty early. It’s consistent with putting an Ambrosia beetle’s nail in the coffin.”
The first symptoms of a diseased tree are mild: a thinner canopy, diminished leaf size and new branches about half the usual length, Clement says. “People don’t notice the size of the leaves, how thin the canopy looks, if you can see light through the canopy – those are subtle indications that things are on a less normal path.”
The symptoms then shift to sawdust from the beetles attacking the trunk, he said. “You start to see these organisms, and people ask, ‘What can I do?’ Well, it’s too late for remedial action. “
Dying oaks suffer a lot of blows – and conditions caused by humans can exacerbate the problem, experts say.
In the interview, when Rane and Clement saw a picture of the retaining wall around the base of the tree, they both exhaled. “Retaining that wall around the tree wouldn’t have helped if it had climbed over the past 10 years,” Clement said. “If that tree is a 25-year-old tree, it’s probably not going to struggle or have that effect. But an older tree, if you start doing things around that, any root disruption, they is a lot more sensitive. It’s harder for them to recover. “
“Some of the trees in this yard are dying from TLC,” Rane added.
Aga Jones said a thin stack of bricks surrounded the tree when they bought the house. The Joneses fortified it and built it shortly after moving.
Experts say that retaining walls, building near trees or even piling soil can take away oxygen from the roots, and the larger the wall, the worse it is for the tree. The builders did warn the Joneses that they could not afford to build the wall too high because it would stress the tree, Jason Jones said, adding, “That was something we thought about when we built the wall, but we thought that it’s a calculated risk. “