Five wheat fields have been confirmed positive for Wheat streak
mosaic virus (WSMV) in southern Alberta from Pincher Creek to Medicine Hat.
WSMV is a pathogen that is endemic to Alberta and shows up occasionally in
wheat and winter wheat crops, but rarely on barley. The last time Alberta had a
WSMV outbreak was 2015 and 2016.
The virus is vectored by the wheat curl mite and the mite and
virus don’t normally overwinter unless they find a “green bridge” host such as
winter wheat or perennial grasses. Volunteer wheat is very often the source of
outbreaks. Most of the positive fields in 2022 were the result of winter wheat
volunteers or herbicide escapes.
If you suspect WSMV and need help confirming it, you can contact
Alberta Agriculture, Forestry and Rural Development (Dr. Michael Harding and
Dr. Jie Feng) to have a laboratory test performed.
michael.harding@gov.ab.ca or 403-362-1338
There are no in-season remedies or management tools, so when
fields are infected early (tillering or earlier) they should be terminated.
When fields are infected after heading, yield losses are usually minimal. There
are no effective insecticides.
Tillage or swathing/baling is recommended, followed by
glyphosate application. This prevents the mite migrating to neighboring crops.
Grazing is not recommended.
Nitrogen fertilizer applications will increase mite numbers and the
virus will spread more rapidly.
Successful management will depend on management of ‘green
bridge’ hosts from 2022 to 2023. This can be done by delaying the seeding of
winter wheat until after the spring crop has been harvested completely, and
controlling volunteers in the spring.
More detailed information can be found at the links below. Or
you can listen to the American Phytopathological Society Podcast (Plantopia) on
WSMV:
https://www.plantopiapodcast.org/22
https://apps.msuextension.org/montguide/guide.html?sku=%20MT200911AG
https://extensionpublications.unl.edu/assets/pdf/ec1871.pdf
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| Wheat streak mosaic virus (WSMV) in southern Alberta, photo courtesy of Michael Harding, AFRED |
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| Wheat streak mosaic virus (WSMV) in southern Alberta, photo courtesy of Michael Harding, AFRED |
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| Wheat streak mosaic virus (WSMV) in southern Alberta, photo courtesy of Michael Harding, AFRED |
Michael Harding, Crop Health Assurance Lead
Agriculture, Forestry and Rural Economic Development
Brooks, AB
