Beech Leaf Disease
Beech trees, both the American beech Fagus sylvatica and the European beech Fagus grandiflora, are among the most important and beautiful trees in our forests and landscapes. In native woodlands of Pennsylvania, the beech is considered a climax species; that is, one that can germinate and grow with limited resources. The beech is shade tolerant and will grow for centuries. Its nuts feed over 30 species of animals, and its unique bark and canopy are unmatched in beauty and grace. European beech trees are prized for their beauty and diversity; gardens and landscapes all over the world showcase European beech specimens as focal points. The list of European beech cultivars is long: in Southeastern Pennsylvania we see copper-leaved, weeping, fastigiate, and fern-leaved cultivars gracing landscapes, campuses, and gardens.
Sadly, a serious disease is threatening all beech trees. Beech Leaf Disease (BLD) was discovered in Ohio in 2012, moved steadily east to our neighbors in New England, Connecticut, Maine and New York, and has finally arrived in our service area. BLD is caused by a leaf- and bud-dwelling nematode. The nematode infects leaf and bud tissue causing leaf distortion, bud damage, twig and branch death, and eventually death of the host tree. Tree death can occur in five to six years.
Researchers and arborists have been working to try to understand BLD and establish effective treatments. So far, we have three different tools with which to help protect beech trees:
A phosphite treatment, which we have successfully used for 20 years to help European beech trees deal with another devastating disease called Phytophthora. Phosphites seem to enhance trees’ ability to fend off certain pathogens and become more stress-tolerant. This doesn’t seem to be a ‘cure’ for BLD, but it showed some promise in an early study done in Ohio.
A foliar spray with a product containing the nematicide called fluopyram. This appears to be very effective but will be limited to trees that can be canopy-sprayed. 100-foot-tall beech trees might not be good candidates for spraying.
A root flare injection of a product called Arbotect. This is the same product that we use to protect against Dutch Elm Disease in American elms. Arbotect can move to all parts of the tree canopy and kill the nematode. It seems to last for two years in beech trees. The downside of Arbotect injection is the application’s price. It might be a perfect solution for a property with a handful of beech trees, but it would be prohibitively expensive and impractical to treat a woodland with Arbotect.
We recommend that any of our clients with beech trees contact us so that we can have a conversation about how we can use the approach that makes the most sense to save these beloved and valuable trees.
