Latest Update on Beech Leaf Disease in New England
Beech trees are a keystone species in many ecosystems. Their fruit – the beechnut – is a food source for many animals, including squirrels, deer, birds, and bears. Their canopies shelter animals and provide nesting sites for birds. Their wood is solid and hard with a beautiful grain. Beeches are also famous for their fall foliage and smooth bark. Plus, they have some cultural significance. Ancient people used their bark as paper.
But beeches are under attack now from Beech Leaf Disease (BLD), a deadly disorder that threatens native American beeches and ornamental European beeches. Researchers first detected BLD in Ohio in 2012. It then spread to other states and Canada. It’s now in 12 U.S. states and several Canadian provinces. Researchers found BLD in CT in 2019 and RI and MA in 2020. BLD is especially deadly to young beech trees and the ecosystems they support.
What is Beech Leaf Disease?
Nematodes cause BLD. These microscopic worms (Litylenchus crenatae mccannii) spend the winter in beech buds and beech leaves and emerge in the spring, showing damage to the tree. Infected leaves have dark brown bands between leaf veins or are crinkled, smaller, and leathery than typical beech leaves. Symptoms are more noticeable on North American beeches than on European beeches.
Some beech buds won’t open on heavily infected trees. Severely damaged leaves will fall off soon after emerging in May. New leaves may appear in June in new buds and won’t show signs of the disease, but they will be paler and weaker than typical healthy leaves. Wind plays a big role in spreading the disease. So does the movement of infected plant material like firewood or nursery stock. BLD can spread fast in a forest
Impact of Beech Leaf Disease
Researchers are seeing beeches die within 6-12 years of infection. In Southern New England, beeches often die within a few years of infection. The disease’s effects on trees are critical. Like many tree diseases, BLD reduces photosynthesis and growth and increases susceptibility to other pests and diseases that can kill trees. BLD also causes loss of biodiversity and alteration of the forest ecosystem. Plus, it impacts the timber industry and tourism.
Researchers are working on management solutions for BLD. But there isn’t a cost-effective solution for forested environments yet. There are no effective fungicides for BLD, and treating large mature trees is difficult. Management options are limited but include the following:
- Early detection and removal of infected trees
- Development of resistant beech tree varieties
- Biological control agents
- Public awareness and education campaigns
In 2017, Ohio researchers had some success managing the disease by treating the soil around small beech trees (about 2-4 inches deep) with a phosphite product called PolyPhosphite 30. Phosphite products are known to stimulate a plant’s defenses.
The researchers treated the trees twice a month with the product about a month apart. The trees were much better after five years than the untreated control trees. They also found fewer nematodes on treated trees than on control trees. We hope to see similar results in New England.
How to Treat Beech Trees
Phosphite products for BLD are available to homeowners. Look for a product that is designed for BLD treatment. Agri-Fos and ProPhyt are good options for BLD. These products are in liquid form. Below are the seven steps to treating a BLD outbreak using a phosphite-based product and a soil drench approach:
1. Measure the tree’s diameter at breast height—about 4.5 feet high
2. Follow the product’s label instructions for dosage
3. Mix the product with water according to the label
4. Clear the area around the tree’s base of debris and leaf litter.
5. Slowly pour the diluted phosphite solution into the soil.
6. Let the solution soak into the root zone.
7. Water the soil after application to help the solution penetrate deeper
Treat BLD in early spring before new growth begins. You may need to treat the area again later in the growing season. Depending on the disease’s severity and dosage instruction, you may need to treat the soil again.
You can also use a soil injection method to treat BLD. However, you need special equipment to inject phosphite into the soil around the root zone. Follow the manufacturer’s instructions for injection depth and spacing.
If you still have questions about BLD or its treatment, contact an arborist or RITree.