Q&A with Extension Agent Associate John Hooven
Beech leaves infected with BLD showing characteristic dark green banding along leaf veins.
Image Credit: Jim Chatfield, OSU Extension
Often seen as symbols of strength and permanence, many large forest trees have begun to look remarkably vulnerable to the stresses of sharing the planet with humans, from climate change to invasive pests transported from one corner of the world to another. Some scientists predict that 100 tree species could be wiped out in the coming decades.
The latest threat has been marching across northeastern forests, killing one of the most common and abundant types of trees throughout our region. Beech Leaf Disease (BLD) has been devastating all species of beech trees, from ornamentals used in landscaping to those smooth-barked, 120-foot-tall behemoths that people like to carve their initials into.
University of Maryland Extension Agent Associate, John Hooven, has first-hand experience surveying a forest that was hit with BLD in 2021 in Cortland County, New York. We sat down with him to get some basic facts about this new and still-mysterious disease and what it means for concerned Marylanders.
What is beech leaf disease or BLD?
Beach leaf disease is a foliar disease, meaning it affects the leaves of the tree, and it’s caused by a non-native nematode, which is a microscopic type of worm-like organism. It was first identified in Ohio in 2012, and has since spread across the Northeast. It’s been identified in 11 states and Ontario, Canada, and the consensus is that it’s in Maryland, based on observations in both Pennsylvania and Virginia. Maryland Department of Agriculture has been actively looking for it but has yet to identify it here.
How bad is it? Could it wipe out beech trees like Dutch elm disease did?
That seems to be a possibility, but there are still a lot of unknowns. It seems to impact young beech trees more than older ones, but both are affected, including very large trees. Mortality occurs within two to seven years, and there is no known remedy to date, no way to mitigate it. That’s concerning because it’s spreading rather fast for a tiny little nematode. There is the idea that it could be treated with some sort of spray, but in a forest setting, that’s not going to be practical.
Are we at all prepared, and if so, what tactics are forest managers using?
At this point in time, we're just in an observe and report mode. Wherever it’s found, it’s good to get that information back to the researchers and the labs that are working on the issue. There are some trials going on in Ohio to investigate different treatment options such as the use of one chemical that can strengthen trees’ resistance to the disease or injecting insecticides directly into tree stems to kill the nematodes without hurting other insects.
How important are beech trees to Maryland forests?
Beech trees are very important to the whole region. They’re some of the most common trees in Maryland forests, and they can live for hundreds of years. They provide important habitat for birds and small animals, and their nuts are edible, so they provide food for species such as bear other animals. Beech trees are also shade tolerant, so most species will grow in established forests where other trees won't, which means they fill an important ecological role in the forests.
What can I do to protect my beech trees?
Since it’s still unknown how it’s being vectored, it’s very important not to move materials from potentially infected areas to uninfected areas. That includes any yard debris, firewood, leaves, soil, seedlings and things like that. Landowners with beech trees on their property should monitor their trees for the symptoms of the disease and avoid moving materials around their property.
These are the same precautions that can help reduce the spread of other invasive pests, too, like the spotted lanternfly and the emerald ash borer, because generally invasive species are hitchhikers.
How can I identify it?
What’s most identifiable about BLD is the banding between the veins of the leaves, especially when you are looking up into the canopy from below. If you’re looking at lower leaves, you can turn the leaf over and see it from the underside. You’ll see alternating dark green and light green stripes, and the leaves will look leathery and curled. Eventually, the leaves wilt, turn yellow and die.
What’s really important is that there is a look-alike, a native beech leaf rolling aphid that appears strikingly similar, but it’s native and doesn’t have an impact on the tree. The aphid causes yellowing and curling of the leaves, that can be mistaken for BLD. But it’s the banding, or striping of dark green and light green that indicates it’s BLD.
What should I do if I see it?
If you suspect beech leaf disease, you should report it to the Maryland Department of Agriculture’s Forest Pest unit by emailing them at fpm.mda@maryland.gov or call 410-841-5870.
MDA also recommends disinfecting your shoes with a solution of bleach and water immediately after walking through stands of infected trees, so if you think you’ve seen BLD, it would be good to take that extra precautionary step.
Is there anything else people should know about this disease?
If I had to leave one take away about the issue, our society needs to do more about preventing the spread of invasive species. An ounce of prevention, as they say. . . It is not sustainable to invest in control after a species invades. Humans are the number one invasive species. It’s our responsibility, therefore, to steward the lands and prevent and correct the spread of invasive species across the landscape.
To learn more about how to prevent the spread of invasive species, visit:
The Nature Conservancy’s Invasive Species Education page
or
The Alliance for the Chesapeake Bay
Also, consider becoming a woodland steward to become an advocate for forest and wildlife stewardship in your community. Enrollment in the Delmarva Woodland Stewards Program starts soon.
