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Oak wilt

Oak wilt found in Canada

Oak wilt has been found in the following locations:

Oak wilt is a disease caused by the fungus Bretziella fagacearum. Red oaks are particularly susceptible, resulting in tree death within a single season. Oak wilt is spread naturally through root grafts or beetles carrying fungal spores. Oak wilt does not affect human or animal health.

What you can do

Report oak wilt

Signs and symptoms of oak wilt

The signs of oak wilt are:

Symptoms of oak wilt are characterized by a wilting and bronzing of the foliage, starting at the tree top and tips of branches, and spreading rapidly throughout the entire crown. Symptoms develop beginning in May and continue throughout the growing season. Individual leaves turn bronze progressively, from the tip to the base, sometimes leaving a small area of green tissue at the base around the center vein of the leaf.

Types of oak tree and leaf decline not due to oakwilt

Frost damage

Frost damage or nutrient deficiency can sometimes be confused for oak wilt. Signs of frost damage include random patches of browning, dead, or shriveled and wilted leaves. Many oak trees can recover from frost damage.

Nutrient deficiency

Oak trees require certain nutrients for healthy growth. Signs of nutrient deficiency depend on what nutrient is lacking, but can include random patches of yellowing, mottling, or misshapen leaves, typically new growth. Sometime fewer leaves may be produced or shoots may begin to grow from the base of the tree. Many oak trees can also recover from nutrient deficiency if it is addressed appropriately.

Leaf senescence

As oak leaves naturally age throughout the growing season and autumn approaches, chlorophyll production stops and the vessels that carry water and nutrients to the leaves are closed off. This results in the green pigment within the leaf degrading, revealing yellows and reds throughout the entire crown. The leaves will also begin to dry out, crinkle, curl, and become more easy to tear as the natural process of senescence occurs, followed shortly by leaf fall. This differs from oak wilt symptoms which begin in the upper canopy and do not lead to any kind of leaf curling or deformation.

What we are doing

To help prevent the spread of oak wilt, the CFIA is conducting surveys in the affected areas. As part of the survey, a Notice of Prohibition of Movement and/or a Notice to Dispose may be issued to affected property owners. These notices are issued by the CFIA to reduce the risk of spreading a plant pest/disease. Any movement and/or activities of specified materials must be authorized in advance by the CFIA.

Tree removal will occur if trees are suspected of having oak wilt and/or are in close proximity to oak trees known to be infested. If these controls are not carried out, oak wilt disease may spread. While it is a slow moving disease, if oak wilt becomes established, it could have a major impact on Canada's natural resources and forest industries.

We continue to work with other federal, provincial and municipal governments on communications, surveillance and response planning.

More information

Policy directives

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