American beech: ‘Appreciate them while they’re here’

The American beech is an iconic tree in the Island’s lush forests, standing apart from the wrinkled trunks of oaks and the evergreen needles of pines with its smooth, pale bark and dense leaves. 

But an infestation of microscopic worms is causing a tree sickness called beech leaf disease (BLD), which is impacting beech trees across North America, including on Martha’s Vineyard.

This summer, when hiking in Cedar Tree Neck Sanctuary, Islanders might have noticed the shriveled, curled, and browning leaves on the forest groves of American beech, Fagus grandifolia. Local experts have confirmed that the beech forests are being impacted by beech leaf disease, which was first documented in Ohio in 2012. 

Since then it has reached most Northeastern states, including New York in 2016, and Rhode Island and Massachusetts in 2020. Today, symptomatic trees have been found in every county in the state, according to the Massachusetts Department of Conservation and Recreation Forest Health website. Both the American beech and the European beech varieties are susceptible to infection. 

Beech leaf disease stands as the No. 1 threat to the longevity of beech forests in the country, and there is no known treatment for the ailment that’s been approved for natural landscapes. The cause of the disease is Litylenchus crenatae, a microscopic worm, also referred to as a nematode, that has been identified as originating in Japan, though it did not result in as severe disease in Japanese beeches. The worms cause BLD by invading and damaging the buds and leaves of both young and mature beech trees. The disease is thought to be spread by birds and other insects, according to a study from the University of Massachusetts Amherst. 

Symptoms of BLD include dark striping of the leaves between the veins of the leaf, browning and curling of the leaf, leaves that are smaller in size, and reduced foliage and branch die-off. A tree that is severely plagued could have few or no leaves at all. This inevitably leads to the death of the tree, as leaves are the tree’s critical method for photosynthesis. 

The nematode joins several other invasive species that have been notably impacting North American ecosystems, like New York’s lanternfly infestation, and more locally, the Island’s Southern pine beetle infestation.

According to Island experts like Adam Moore, president of the Sheriff’s Meadow Foundation, the infection was first identified in Aquinnah, and has been progressively spreading to the other up-Island towns. 

“In a forest setting, we are not taking any active measures,” said Moore. “The nematode is new. No one quite knows what to do with it, so we’re taking a very passive approach.” 

Beech trees were already under attack from another threat, beech bark disease, a fungal infection that has taken its toll on forests across Massachusetts. Native, coastal beeches have been able to withstand infection, and have been dodging the disease. 

Harvard forester, author, and paleoecologist David Foster says that makes the Island’s forests quite remarkable. 

“They are magnificent,” Foster said. The loss of the seemingly resilient trees to BLD “is doubly tragic,” he said. 

“You can see it clearly, at Cedar Tree Neck Sanctuary, where we have lots of American beeches throughout the property,” Foster said. “If you want to see it firsthand, that’s where I’d recommend.” 

The trees have also been noticeably affected at the Menemsha Crossroads, where North Road and South Road meet. The beech tree in the center green is notably withered. 

According to researchers and findings in Ohio, trees are starting to die after two or three years of living with BLD. Foster speculates that between four and 10 years from now, most of the existing wild beech trees will have perished if the disease continues to go unchecked. 

As for Island trees, Moore says he hasn’t noticed any dead beeches yet, but that he anticipates the loss. After the native varieties of oak and pine, beech trees are one of the Island’s oldest and most prevalent tree species, having been present on the Island for thousands of years. 

“You can safely say that there is no single tree species that had a greater impact on shaping the first environment of Martha’s Vineyard than beech trees,” said Foster of the historic significance of the beech. “The diversity of environments, habitats, and human experiences is going to suffer from the loss of the beech.”

Foster is the author of “New England Forests Through Time” and “A Meeting of Land and Sea: Nature and the Future of Martha’s Vineyard,” among other titles. 

Being the third most significant component of Island forests, beeches provide important habitat like nesting sites and edible nuts for birds and other wildlife. Though Foster had anticipated the continued prevalence of the beech, he believes forests would adapt without them. 

Moore, at Sheriff’s Meadow, speculates that holly trees might rise to the opportunity, and capitalize on the newly available sunlight and open space.

While there are no approved treatments for wild beeches, treatments for privately owned trees are still being studied. A report from UMass Amherst’s Landscape, Nursery, and Urban Forestry program stated the use of phosphites and nematicide products can effectively control BLD, though results have varied. Phosphites can be applied to the soil for root uptake, and commercial products containing fluopyram like Broadform can be sprayed on the tree as a preventive measure at the first signs of disease, and on heavily infested trees during peak reproductive season, late July through October. 

“There are some really magnificent beech trees on the Island in people’s yards, both American beeches and European beaches. I would be concerned if I owned one of those; I’d look for a way to protect it,” said Moore. 

While there have been proactive approaches to fending off the Southern pine beetle in ways that are not harmful to the forest, treating natural and protected forests for BLD with either of the studied methods would have detrimental effects on the overall ecosystem.

Foster cautioned against too much human intervention in nature’s process. “We have this great egotism that nature needs our help, but most of what we’re trying to do is make things so they’re better for us,” said Foster. If a dead beech tree should pose a safety hazard to someone’s house or property, felling trees is appropriate. “The vast forests of beech are better left alone so that nature can take its course,” Foster said. 

“Appreciate them while they’re here,” he said. 

Other efforts to combat BLD include studying the affected trees, the nematode’s behavior, and identifying possible natural predators or pathogens that could help control the nematode population. 

“Often with infestation, whatever is causing it succumbs to some other kind of pathogen,” said Moore, like a predator or a fungus that could prey on the nematode. “But I don’t know if that will happen here.”

“I think eventually the American beach will overcome this pest and find some kind of way to resist,” speculated Moore. “But that doesn’t mean it will happen in our lifetimes, or even in several generations of human lives.” 

That, of course, is pure speculation, Moore said. Speculation, and hope. In nature, the specifics and the outcomes are largely unpredictable.