Beech Trees in Peril

– This article, by Marnie Lacouture, first appeared in WildfloraRI, Winter 2022

While walking in the Arcadia Trail in Exeter in late May [2022], tagging along with Shannon Kingsley who was searching for golden groundsel (Packera aurea) for the Reseeding RI project, something seemed uncomfortably amiss. While Shannon was watching the ground, I was looking up at an almost leafless canopy. In what was a forest of mostly beech trees, there were few leaves, and the ones that remained were crinkled, with dark edges. After checking with a DEM forester I learned that the trees were under attack from a microscopic nematode (Litylenchus crenatae) that causes Beech Leaf Disease (BLD). Would they recover? I asked him. Not sure. Would they die? Not sure—maybe.

According to Heather Faubert, Director of URI’s Plant Protection Clinic, BLD was originally discovered in this country in Ohio in 2012 and has spread eastward across the native range of the American beech (Fagus grandifolia), our only native beech, a stately tree with smooth, gray bark reminiscent of an elephant’s hide. The leaves turn a lovely amber in the fall and are distinctive in the winter woods BLD was first discovered in Rhode Island in the summer of 2020 after an Ashaway landowner contacted DEM about a problem with her beech trees. Heather and a DEM forester found an area five miles in diameter affected with BLD. By the next year infested beech trees had been found in all but Providence and Bristol counties, and this year it has been detected in those as well. Washington County has been especially hard hit in 2022.

The nematode is foliar, living in a beech tree’s cigar-shaped buds and causing dark striping along the veins of the leaves once they emerge. Eventually they may wither and die. Unlike trees defoliated by an insect such as the spongy moth (formerly the gypsy moth) which don’t put out new leaves until late July, beech trees affected with BLD will leaf out again in June allowing them a longer time to recover and to build up reserves for the next year. Heather finds this somewhat hopeful. By the following year though, the nematodes may find their way into the buds, and the cycle will begin again. How the nematodes travel long distances is not known, but since the disease has arrived quickly from Ohio, birds or possibly insects or the wind may be spreading it. Whether they are in fallen leaves on the ground and can make their way to buds is another unknown, as is whether they can travel through the root system of several beeches in a colony.

BLD primarily infects the American beech but can also infect European beeches. Often those are planted as beautiful specimen trees and would be sorely missed in a yard. If a homeowner believes she has a beech infested with BLD, there is a safe treatment being tested by URI and others using potassium phosphate fertilizer. Information may be found on the URI website or the DEM website. If used for several years, it may save a tree.

I returned to the Arcadia Trail in early October to see how the beeches there are doing. They had put out new leaves over the summer, but they didn’t look vigorous, and the canopy was still sparse. After hearing Heather say, “American beech forests may be doomed; it would be a huge catastrophe to lose that unique ecosystem,” I ask her whether it would be like losing the chestnuts (Castanea dentata). She answered that looking at it from a human, economic perspective, losing the chestnuts was worse, but from an ecological perspective she feels it is just as bad. I wonder sadly what our woodlands would be without beeches.