Please Note – this article has been updated, with a new posting entitled Beech Leaf Disease – 2021 Update uploaded on June 16, 2021. CAES is no longer encouraging individuals to report findings of Beech Leaf Disease to the Station.
In August 2019, a new disease that affects beech trees was detected in Connecticut for the first time, along the Mianus River between
Stamford and Greenwich. Beech Leaf Disease was first reported in North America in Ohio, in 2012. It was soon found in areas around the upper Midwest and in adjacent parts of Canada. It has since been moving east, but had not been found in this region until this past year.
The disease is caused by an Asian nematode, Litylenchus crenatae, which attacks both American and European beeches. It is known to kill trees that have been heavily infested over several years. Beyond that, not a lot is known about this organism and the disease that it causes. That includes knowledge as to how it spreads, where it currently is in Connecticut and how it might be treated.
Dr. Bob Marra of the Connecticut Agricultural Experiment Station has taken the lead on researching this disease in Connecticut. He is working with foresters at CT DEEP Forestry seeking to locate occurrences of this disease . He is also very interested in hearing from arborists, tree wardens and others who believe they may have encountered the disease. All information will be helpful.
The disease is not hard to spot during the growing season. The symptoms on the leaves are very evident. Tell-tale is readily apparent, interveinal discoloration, dark-green early in the season and then yellow later on, as the season progresses. This gives the leaves an odd, striped appearance. The infestation, though, may start at the top of the tree. As such, these indications of an infested tree may not be readily visible from the ground. A pair of binoculars or a close examination of a felled tree may help in spotting the disease.