Beech Leaf Disease
Beech Trees of New Hampshire, Massachusetts, & Maine seacoast are struggling. Here's why and how we can help.
Have you noticed that the Beech trees have been looking rather thin lately? Perhaps you have noticed that some of these Beech trees have leaves, but the leaves are distorted, puffy, and have a thick or dark appearance to part of the leaves. You’re right to be concerned if you see this. This odd appearance to the Beech leaf is caused by an invasive microscopic worm called a nematode and it is devouring our native beech tree forests.
To discuss Beech Leaf Disease we need to know we are correctly identifying a Beech Tree. Let’s begin here.
What is a Beech Tree? And It’s Beech Tree, not Beach Tree (those are Palm trees– which aren’t really trees, that is a subject for another day)
Beech Leaves (Shape & Color)
All leaves of beech trees are simple and alternately arranged along the branches. However, they come in a few different shapes. The most common shape is those found on our native American beech trees. These leaves are elliptical to oblong with sharp parallel veins and a toothed margin along the leaf edge. You can find them with a smooth edge and glossy texture like those on our European Beech, Copper Beech, and Weeping Beech Trees. Finally, you can find them with in a lobed form like that of the Cutleaf Beech and Fern-leaf Beech which usually looks almost feather-like in appearance.
You can find the Beech tree in many different colors. The traditional leaf color of the Beech tree is a glossy green color, but you also find beech trees with a deep red-purple color known as a copper beech tree, and the flamboyant tri color featuring purple, pink, white, and sometimes green.
Buds
Aside from using the bark as my key identifier for my Beech tree Identification in the winter I also look at the buds. As an arborist, I am often tasked with identifying a really young tree that has not taken on its characteristic bark. It’s like looking at a baby bird without its feathers. The bud is my key to identifying the sapling. So, for Beech trees the key identifier is that the buds look like a long skinny tightly rolled Cuban cigar with a pointy end.
Bark, Trunk, & Shape
Beech trees are smooth barked trees with a light grey color, which almost have the look of elephant skin. In fact, many clients on the New Hampshire seacoast have shared stories about climbing in a Beech tree as kids, they called these giant trees, “elephant trees.” Perhaps you have a similar memory. Even the branching structure of the Beech can look like the trunk of an elephant. The beech tree’s branches extend far out and often dip low to the ground and root themselves. Beech trees can take many forms, they can be fastigiate (growing narrow and upright), they can have to large sprawling canopy (like the kind you see on college campuses and in front of historic libraries), they can also come in a weeping variety and provide a magical place for young children and adults to gather and build their creative imagination.
Now that you have determined what a Beech Tree looks like Let’s talk about what Beech Leaf Disease is and how it kills the tree
Beech Leaf Disease is caused by a microscopic nematode that overwinters in the buds of Beech Trees. These nematodes are host-specific, so there is no need to worry about other tree species. During winter, they feed within the buds. It is still largely unknown whether their feeding directly causes the distorted, curly, puffy, and often leathery leaves, or if they carry a vector responsible for these symptoms. However, it is known that eliminating the nematode can save Beech trees. As the disease progresses, leaves become increasingly distorted, and a premature drop can occur. This happens because the tree shed leaves that are unable to photosynthesize, rendering them useless. When leaves become too distorted to photosynthesize effectively, the tree will starve.
Older Beech trees have some resilience; they can use stored energy to produce a secondary flush of leaves if they are approximately 10 years old or older. These secondary leaves typically do not suffer from infection, as they develop from buds that did not harbor overwintering nematodes. Despite this capacity, the process is exhausting for the tree, akin to climbing Mount Lafayette without food—possible a few times, but unsustainable over the long term. Young saplings lack the energy reserves to survive without immediate protection of their leaves. Older trees have a greater chance of survival due to their larger energy stores.
Beech Leaf Disease in Leaves
The leaves of infected Beech Trees exhibit distortion with thickened segments between the leaf veins. These segments may feel leathery, stiff, or dried out as the disease progresses. In advanced stages, the leaves may crinkle and drop prematurely in early spring, causing the tree to produce another flush of leaves to feed themselves.
Canopy
While leaves are the primary indicator for diagnosing Beech Leaf Disease, it is also recommended to observe the density of the tree's canopy. A thick and full canopy typically indicates that there is little to no infection of Beech Leaf Disease. Conversely, a canopy that appears thin, sparse, or irregular suggests a high likelihood of Beech Leaf Disease infection, potentially accompanied by a secondary infection.
Secondary Infections
Let's discuss secondary infections. When a tree is stressed, such as by Beech Leaf Disease, it releases a stress hormone that attracts insects like the woolly beech aphid. Treating Beech Leaf Disease can reduce this stress and potentially eliminate the need to treat aphids. However, monitor the aphid population to ensure they remain below the treatment threshold. The photo above shows a very low population level of Woolly Beech Aphids (white fuzzy insects on the underside of the leaf.)
Now it is time for you to look for the disease and be proactive
If you have Beech Leaf Disease on your property, act now. Treatment options depend on your tree’s health, size, and root flare. Consult a Port City Tree Care arborist to determine the best treatment for your tree.
So why is this a problem for Beech Trees now? – Ah yes, I get these questions a lot!
I can tell you in one word, but I’m too much of a storyteller. However, if you’re into cliff notes, here’s the one word, globalization. The story I have heard is that in 2011 it is believed that a Beech Bonsai was brought in the U.S. from an Asian country through a port in and around Cleveland. This is where the disease initially showed up. At first the population slowly moved across the East Coast until the population of nematodes grew in size. Now, their movement is accelerated because they multiplied. The nematode moves with wind, rain, and birds.
Should I be concerned about my other trees?
No, but you should be concerned about all your trees. The nematode causing Beech Leaf Disease is specific to beech trees, similar to how you can’t give your cold to a dog due to genetic differences. This nematode evolved alongside Asian Beech trees, which can coexist with it, unlike North American and European varieties.
What do I do about the distorted leaves on my Beech Tree?
Great question! Call Port City Tree Care Immediately! We can treat your tree either through injections if it is suitable or foliar applications. Treatments need to be specifically timed with the tree’s growth and the nematode. The Certified Arborists at Port City Tree Care can explain the right timing for you and your tree.
TREATMENT IS AVAILABLE
Beech Leaf Disease is the next Chestnut Blight, Dutch Elm Disease, & Emerald Ash Borer. If you wish to save your Beech Tree for future generations please speak with a certified arborist.