Although not an overly common disease, wheat streak mosaic virus can cause an immense amount of damage to final yield.
Reports in southern Alberta have indicated the appearance of the virus. Although alarms aren’t being set off, it’s important to be aware of it, as the virus can spread quickly and easily.
The initial signs include yellowing on new leaves, likely around the borders of the field, says Jeremy Boychyn, agronomy research extension specialist with Alberta Wheat and Barley Commissions, in this Wheat School episode.
The disease is spread through wheat chromites, where the insect pest will infect the wheat.
Although it can be found in all forms of wheat, as well as corn, it predominantly is found in winter wheat.
If it’s been noticed in a field nearby where you plan to plant winter wheat in the upcoming months, it’s crucial to be paying attention to the green bridge — the hypothetical bridge of green leaf tissue that allows the chromite to jump from one host to the next.
“A green bridge is a piece of green material like a weed, or a crop, that can host the disease, and overlaps between crops. So if we put spring wheat in the ground, and through the season that gets infected with wheat chromite, and then before that spring wheat crop is dried down, we seed a winter wheat crop, and then it emerges. We’re now in a situation where we’ve created a green bridge, because the wheat chromite can jump from your spring wheat into your winter wheat,” Boychyn explains. In this scenario, this will also carry wheat streak mosaic virus into the following year, as the winter wheat continues to grow.
Wheat streak mosaic virus can be impactful on yield, and as Boychyn notes, it can cause pretty massive effects to yield and quality, as it shrivels the grain.
“You’ll have this kind of greening striped pattern in the tip of the leaf, and the yellowing mosaic that works around it,” he says. “It’ll continue to move its way down that leaf, and then spread to other leaves from there. And then we start talking about losing photosynthetic leaf area. And that’s where we’re losing yield.”
Currently, there is no in-field control methods for the virus. The best forms of management, says Boychyn, is eliminating the green bridge, watch timing of winter wheat seeding, and following a proper crop rotation.
“We’re not doing wheat followed by winter wheat, and pushing the boundaries of those rotations and green bridges. And we’re also selecting winter wheat varieties if we know we’re at risk for wheat chromite and wheat streak mosaic virus.”
Check out the full conversation between Boychyn and RealAgriculture’s Kara Oosterhuis, below: