Please Note – this article updates an earlier post on Beech Leaf Disease, from June 22, 2020.
In a recent press release, the Connecticut Agricultural Experiment Station (CAES) reported that beech leaf disease has become much more widespread in the state, with an increasing number of findings coming in from a wider area. CAES is reporting that the range of symptoms associated with the disease are also increasing, perhaps due to the association with the dry weather from 2020.
Because of the current extent of beech leaf disease, CAES is not longer encouraging arborists or others to report citing of the disease to the Station.
For people who seek further information on beech leaf disease, CAES is referring people to the US Forest Service Pest Alert on Beech Leaf Disease. People might also review an article entitled An Overview of Beech Leaf Disease, written by Dr. Bob Marra and published in the October 2020 edition of the New England SAF newsletter.
The full CAES press release on Beech Leaf Disease, with pictures, may be downloaded. The text of the CAES press release is as follows:
Beech Leaf Disease Now Widespread in Connecticut
New Haven, CT – Scientists from the Connecticut Agricultural Experiment Station (CAES) have confirmed that Beech Leaf Disease (BLD), first detected in lower Fairfield County in 2019, is now widespread and prevalent on American beech (Fagus grandifolia) throughout Fairfield, New Haven, Middlesex, and New London Counties. It also appears to be spreading into Litchfield, Tolland, and Windham Counties, albeit less severely; to date there are no confirmed observations of BLD in Hartford County. This disease, which can kill trees within several years of detection, was first discovered in 2012 in Ohio, followed in subsequent years by detections in Pennsylvania, New York, and Ontario, Canada.
The symptoms on beech foliage, best observed from below looking up into the canopy, are characterized by dark striping between leaf veins, as pictured below (left). However, this year the symptoms are severe, and can include: aborted leaf enlargement; cupping, browning, and yellowing of foliage; branch and tip dieback; and in some cases, premature leaf drop. CAES and DEEP Forestry believe that 2020’s hot and dry summer, exacerbated by this year’s dry spring, are playing a role in the observed symptoms.
Beech leaf disease is caused by the foliar nematode, Litylenchus crenatae subsp. mccannii. The nematode appears to cause disease on only American, European, and Oriental beech (F. grandifolia, F. sylvatica, and F. orientalis). Scientists at CAES have joined forces with researchers in Ohio, Pennsylvania, New York, Ontario (Canada), and at USDA-ARS to study disease development, transmission, and control.
Research on control options, conducted in Ohio, have not been promising. However, treatments are being promoted by several tree-care companies, for which they claim some success. Property owners may wish to contact their arborist or tree warden about these options.
Given the already well-documented widespread occurrence of BLD in 2021, reports of BLD in Fairfield, New Haven, Middlesex, and New London Counties to CAES and DEEP are no longer requested.
Dr. Robert E. Marra
Associate Scientist / Forest Pathologist
Department of Plant Pathology & Ecology
The Connecticut Agricultural Experiment Station
123 Huntington Street
New Haven, CT 06511