Oak wilt found in Canada
Oak wilt has been found in the following locations:
- City of Niagara Falls, Ontario (first confirmed detection of oak wilt in Canada);
- Township of Springwater, Ontario;
- Town of Niagara-on-the-Lake, Ontario.
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
- Don't prune oak trees between April and November
- Don't move firewood
- Report suspected signs to the CFIA
- Check oak trees for signs of oak wilt
Report oak wilt
Signs and symptoms of oak wilt
The signs of oak wilt are:
- Dull green, brown or yellow leaves
- Premature leaf discoloration beginning on leaf tips and moving in towards leaf centre
- Cracks in the trunk of dead trees
- White, grey or black fungus under bark surface of dead trees
- Early and sudden leaf drop beginning at the crown of the tree
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 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.
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.
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.
- Report of oak wilt in Niagara Falls, Ontario (2023)
- Pest fact sheet
- Oak wilt response framework for Canada
- Science bulletin: Early warning research verifies the oak wilt threat is real
- D-08-04: Plant protection import requirements for plants and plant parts for planting
- D-01-12: Phytosanitary Requirements for the Importation and Domestic Movement of Firewood
- D-99-03: Phytosanitary Measures to Prevent the Entry of Oak Wilt Disease (Ceratocystis fagacearum (Bretz) Hunt) from the Continental United States
- D-98-08: Entry Requirements for Wood Packaging Material into Canada
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