Last year Land Alliance stewardship staff began documenting a worrying condition at our preserves. We witnessed a distinctive striping pattern along the leaves of American beech trees. When standing under a tree and looking up at the leaves, we observed dark bands across them between leaf veins, sometimes alternating with the green leaf color. We had heard about Beech Leaf Disease (BLD); now we were finding it in our preserves – first in the Humes Stroll Garden, then in the Humes Preserve, Cushman Woods, Fox Hollow, Wawapek. And everywhere. Eventually those leaves curled up and dried out.
What is Beech Leaf Disease and Its Impact
BLD first documented in New York in 2018 and in Suffolk County in 2020, is caused by an exotic nematode (Litylenchus crenatae ssp.mccannii), a worm that feeds on beech leaves. The condition can cause tree mortality over time.
Many of us are aware of the devastating impacts of American chestnut blight and Dutch elm disease on native tree populations, but few of us may have lived through the early stages of ravaging such majestic trees. To be experiencing a new disease whose impacts may wipe out entire populations of our cherished beeches – a dominant canopy species in so many of our Long Island woodlands – is sobering. The disease is a serious threat to imperiled community types found on the north shore of Long Island. There is no known treatment for it, but thankfully, research is underway to find one.
Search for a Treatment
The NYS Department of Environmental Conservation, Cornell Cooperative Extension (CCE) – Suffolk County and the Long Island Horticultural Research & Extension Center (LIHREC) recently submitted a new project proposal for a Forest Service Pesticide Impact Assessment Program (FSPIAP) grant. It would provide funding to conduct trials and evaluation of the effectiveness of several pesticides and a fertilizer over a three-year period. As one of three land trust cooperators (in addition to Peconic Land Trust and Henry L. Ferguson Land Trust) the Land Alliance would provide access to American beech populations at one or more of our nature preserves.
Some promising results of trials of a phosphonate fertilizer have been documented. The trials were conducted on saplings by researchers in Ohio, where BLD symptoms were documented in 2018, and by Bartlett Research Labs of the fungicide Broadform to reduce nematode levels. There also have been successful trials. While Long Island is one of the worst hit areas of the State, given the disease’s recent appearance there has been little time to find a treatment here. CCE – Suffolk County and LIHREC set up monitoring stations in eastern Long Island in 2019 and in 2020 began trials of experimental pesticide treatments. Peconic Land Trust, with a grant through the New York State Conservation Partnership Program, began working with CCE to conduct trials of a fungicide and two insecticides earlier this year. The FSPIAP funding would be used to continue these research trials and launch additional trials of Broadform and the fertilizer used in Ohio at Henry L. Ferguson Land Trust and Land Alliance preserves.
Data collection will be carried out according to the USDA Forest Service BLD long-term monitoring protocol. Visual observational data will be done in May and early September. Leaf samples from each of the treated trees will be collected in early fall for nematode extraction to gauge effectiveness of the pesticide treatments under the guidance of Margery Daughtrey of the LIHREC.
Time is of the essence to find effective treatment of Beech Leaf Disease. The Land Alliance is cautiously hopeful that this important research will contribute to preserving beech trees, whether in New York or beyond our region.
Many thanks to the DEC’s Jessica Cancilliere and CCE-Suffolk County’s Mina Vescera for submitting and sharing their grant application and to Margery Daughtrey for project coordination.