May 22, 2024

New Beech Leaf and Bark Diseases Threaten Princeton’s Beech Trees

To the Editor:

Over the next 10 years, Princeton appears fated to lose nearly all of its beech trees. A new disease, called beech leaf disease, is sweeping through our nature preserves and neighborhoods. It’s caused by nematodes — a worm tiny enough to overwinter in the beech’s long, coppery buds, causing contortions and curious stripings in the emerging leaves.

Information online is not encouraging. Since first being discovered 12 years ago near Holden Arboretum in Ohio, it has spread quickly, extending thus far south to Virginia and east to Maine. Though I had heard rumblings of some sort of disease affecting beech trees, I managed to keep my head in the sand, basking innocently in the beauty of the great tree’s smooth gray bark, admiring its dramatic root flare and towering canopy. In the Institute Woods, there’s a massive beech with a split trunk you can walk through.

My innocence was shattered a week ago, when I spotted the contorted leaves while walking the red trail through a section of Herrontown Woods containing thousands of beech. Mountain Lakes is reportedly affected, and a walk through Autumn Hill Reservation confirmed that the crowns of nearly all beech trees are beginning to thin. Yesterday evening, I stopped by the fabulously multi-trunked European beech on Constitution Hill. Its leaves, too, are showing early signs.

There are actually two new diseases. Beech bark disease also poses a mortal threat. Both are caused by introduced invasive organisms against which the American and European beech have evolved no defense.

Some would say that change is a constant in the world, but it’s the rate of change that determines the trauma, much as the speed of a traffic accident determines the damage done. Nature has no time to adapt. Beech leaf disease arrives barely 10 years after the emerald ash borer began reducing our ash trees to skeletons. Many of our pin and red oaks are succumbing to bacterial leaf scorch. The American chestnut struggles to return.

Though we no longer have towering elm or ash, and fewer oaks, younger specimens are still around. What is striking about beech leaf disease is that it reportedly kills young and old trees alike, and no preventative has been discovered. We can hope that a few beech will prove resistant, but otherwise its distinctive beauty and many ecological benefits to wildlife and people will be lost. As a friend noted, comparing the snail’s pace of tree research to the quick response to COVID, where is science when we need it?

Outrage is often triggered by the intentional cutting of trees. The highly visible  spotted lanternfly caused a stir, yet has proven relatively innocuous. The biggest threats we face are neither visible nor intentional. The emerald ash borer is hidden behind bark. Nematodes are microscopic. Our machines’ climate-radicalizing carbon dioxide? Unintended and invisible.

There is so much joy still to experience, for me particularly in Herrontown Woods, and yet in the larger workings of the world, so much to grieve.

Steve Hiltner
president, Friends of Herrontown Woods
North Harrison Street