For centuries, the Blue Hills has been a sanctuary for countless species of animals, trees, plants, and mushrooms. But in recent years, a threat to its sanctity has been looming behind the scenes: Beech Leaf Disease.

Beech Leaf Disease (BLD) is caused by the Litylenchus crenatae mccannii, an invasive species of nematode, a parasitic worm. It is a fatal disease that causes the leaves and branches of the tree to slowly dry up, shrivel, and die, eventually leading to the tree’s death.

According to the Boston Globe, BLD can kill “up to 90% of young trees in two to five years” in highly infested areas. It spreads very rapidly from tree to tree and can infect whole forests in a matter of months.

It is this rapid spreading of the disease that makes it such a threat, not how quickly it kills the tree. According to the USDA, “tree saplings infected with BLD usually die within five years of infection,” while mature trees can take “several years to die of the infection.” While that may seem like a long time, many of these trees have existed in our forests for centuries, so five years is nothing compared to a tree’s lifespan.

BLD was first discovered in Ohio in 2012, and it has since spread throughout the Northeast US, even reaching the Ontario province in Canada. Despite the fact that researchers have known of the disease for over a decade, scientists are yet to develop a working cure or prevention for the disease.

Beech Leaf Disease first reached Massachusetts in the Summer of 2020. First discovered in Plymouth, it has since spread to “83 communities in Massachusetts” according to the Department of Conservation & Recreation (DCR). Since then, it has spread to the Blue Hills, where Milton High students in Mr. Young’s Exploring Nature class learned of its danger for the first time.

Last Wednesday, the class took a field trip to Hancock Hill to experience the Blue Hills with Mr. Thomas Palmer, the author of the book "Landscape with Reptile," a book exploring the beauty of the Blue Hills, as well as the long history of rattlesnakes in the area.

While hiking up the trail, Palmer stopped the class to point out a seemingly normal tree. He plucked a leaf off of its branches and showed it to the class. “See how this leaf is wrinkled?” he asked. “That’s not normal. Normally the leaf would be flat. These wrinkles are a sign of Beech Leaf Disease.”

He went on to talk about how large of a threat BLD is to the Blue Hills. The DCR recorded that beech trees are the 4th most common tree species in the Hills, composing over 6% of all trees, totaling nearly 18,500 across the whole reservation. But that number could plummet in the coming years.

Palmer told our class that unless a cure is discovered soon, “you guys may live to see the Blue Hills with no beech trees.”