The researchers developed a new detection tool for the beech leaf disease nematode

Beech leaf disease is a new threat to North America’s forest ecosystems. It was first discovered in northeastern Ohio in 2012, and has since spread to another 12 US states and Canadian provinces. At first the cause of the disease was unknown, and diseased and dying trees were diagnosed on the basis of symptoms alone: ​​Dark streaks along the veins of the leaves and leathery, shriveled leaves. But in 2017 nematodes were found on diseased leaves, and in 2020 we have the answer: a newly recognized subspecies of worm-like creatures, Litylenchus crenatae mccanniidefinitely associated with symptoms.

To monitor the spread of the disease, to understand the presence of nematodes among symptomatic and possibly asymptomatic trees, and to begin developing control measures, forestry professionals need a fast and accurate method for detecting nematodes. Previously, forest health professionals wishing to diagnose trees had to go through a slow process that involved soaking the leaves for twelve hours, preparing further samples, and then looking for nematodes under a microscope. This is a good method for an expert to study a single tree, but not one that can be used immediately on a large scale.

In the new report, published by forest health researchers at the Holden Arboretum, the Ontario Forest Research Institute, and the US Forest Service, the team describes a new tool for detecting this nematode. Their work appears in the journal Plant Diseases.

This new nematode detection tool uses long-used laboratory methods to detect specific DNA in certain organisms. In this method, the researcher uses short DNA sequences specific to the species of interest, called primers, to identify and then amplify the target DNA in the sample. The amplification step is a relatively basic laboratory technique, PCR, but the real challenge lies in developing the primers in the first place—which is exactly what researchers have been doing.

“This new primer will make detection of North American beech leaf nematode faster and easier, enabling forest health professionals across the US and Canada to better monitor this emerging disease,” said David Burke, Vice President of Science and Conservation at Holden Forests. & Gardens, which led the work. “Better detection will mean more accurate monitoring and better treatment studies.”

New primers can be used to differentiate L. crenatae from other nematodes that may be found in the area affected by BLD, and also allows researchers to estimate the relative degree of nematode infestation among samples.

“We need all the forest professionals we can get working on BLD if we are to nip it in the bud,” says Burke. “Our forests may depend on it.”

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Quote: Burke, David, et al. “Development of special primers for the detection of Litylenchus crenatae, the causative agent of beech leaf disease, in plant tissues.” Plant Diseases (2023). DOI: 10.1094/PDIS-12-22-2911-SR

About Holden Forests & Gardens: Holden Forests & Gardens comprises two of Northeast Ohio’s most important environmental and cultural institutions — the Holden Arboretum and the Cleveland Botanical Garden — whose mission is to connect people to the magic, beauty, and value of trees and plants, to inspire action for healthy communities. One of the largest public parks in the country, Holden Forests & Gardens has 18,000 member households and an annual attendance of nearly 350,000 people with whom we strive to provide an inspiring and educational visitor experience. For more information, visit holdenfg.org.

Media Contact:
Anna Funk
Specialist Communication Studies
Holden Forest & Gardens
(email protected)

Corresponding author:
David Burke
Vice President for Science and Conservation
Holden Forest & Gardens
(protected e-mail)
440-602-3858