Officials warn farmers of Wheat Streak
With more than a dozen fields confirmed to have had Wheat Streak Mosaic Virus in 2016, and widespread contagion south of the border, Alberta Agriculture and Forestry is advising cereal grain farmers in the southern Alberta to be vigilant.
“We have seen a few fields already which have symptoms consistent with Wheat Streak Mosaic,” confirms plant pathologist Mike Harding, with Alberta Agriculture and Forestry. “We are keeping an eye out for it, and we’re trying to get the word out to be scouting for symptoms. And have anything suspicious tested.”
Wheat Streak Mosaic Virus has no known treatment or chemical control method, and is spread by microscopic, four-legged, worm-like “drybulb” mites. The mites are not the source of the disease but are its primary vector.
As the mites move between grain plants, the disease spreads to the leaves. Wheat Streak Mosaic Virus gets its name from its primary symptom: Yellow streaks that spread through the green leaves of the crop.
Harding says usually a colder winter takes care of the problem, by killing off the green plant material the mites need to survive. Unusually this year, despite colder conditions, the mites appear to have survived. He suspects that’s due to late season volunteers creating a “green bridge” for the mites into this year’s winter wheat crop.
There is very little farmers can do once this virus gets established in the crop, says Harding; all they can do is plough the crop if it’s early in the season or cut it for green feed later on. The best cure is prevention, he says.
“If you are growing wheat, the best way to manage this disease is to make sure there is no green bridge from season to season. That means controlling volunteers and seeding winter wheat late enough that the virus and the vector die out before the winter wheat comes in.”