The Threat of Beech Leaf Disease, Ontario
The American Beech is a common sight in our woodlands, but now it’s facing a new threat – beech leaf tree disease, Ontario. Beech Leaf Disease is a relatively new disease, but is becoming an increasing problem in Canada. This blog post explains what beech leaf disease is, how it spreads, its impact on trees, early and later signs of infection, treatment possibilities, preventative measures, and guidelines on checking your trees for signs of beech leaf disease.
What is Beech Leaf Disease?
Beech leaf disease (BLD) is a relatively recent tree disease in Ontario that primarily targets beech trees (genus Fagus). It causes widespread defoliation by affecting the infected trees ability to photosynthesize.
What causes Beech Leaf Disease in Ontario?
Beech Leaf Disease is not completely understood at the current time, but scientists believe that a microscopic worm, or nematode, named Litylenchus crenatae mccannii causes the symptoms associated with Beach Leaf Disease.
These microscopic nematodes feed on plant tissues and disrupt normal cellular functions which leads to the characteristic symptoms of beech leaf disease. While the nematodes themselves are tiny, their impact on beech trees can be extensive, causing defoliation and weakening the overall health of the affected trees.
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Species of Trees Susceptible to Beech Leaf Disease in Ontario
Beech leaf disease primarily affects beech trees, and the two main species found in Ontario are:
American Beech (Fagus grandifolia): This native species is a dominant component of Ontario’s woodlands and is particularly susceptible to beech leaf disease.
European Beech (Fagus sylvatica): An introduced species, European beech, is also vulnerable to BLD, although the impact of the disease on this species may vary.
It is possible that other species of trees may be shown to be vulnerable to Beech Leaf Disease.
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How is Beech Leaf Disease spreading through Ontario?
Beech Leaf Disease was first found in Ohio in 2012. Since then, the disease has spread rapidly and was found in Ontario in 2017. The exact mechanism of how beech leaf disease spreads is still under scientific investigation. Scientists know that the disease is not caused by a fungus or a bacterium, as is often the case with other tree diseases.
They know that the feeding activity of the nematodes on the leaves and buds of beech trees is responsible for the symptoms but don’t know exactly how it spreads between trees. They think that the nematode either produces something that is poisonous to the trees or that there is another pathogen involved which is linked to the nematode in some way.
What is clear is that BLD spreads very quickly. The spread does not appear to be influenced by tree position or soil conditions. Other nematodes are spread by mites, insects and animals or by infected plant material so this may be the way that the disease spreads from tree to tree.
