LETHBRIDGE – Stripe rust is appearing in southern Alberta, but wheat producers have time to protect crops.
“I think it is very important that producers in the Lethbridge region are aware of the threat,” said Byron Puchalski, who works at the Lethbridge Research Centre for Agriculture Canada.
Outbreaks may occur in irrigated areas of southern Alberta.
Stripe rust is a significant disease for wheat and barley worldwide. It has been in Alberta for decades but the incidence and severity have increased dramatically in wheat since 2003.
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The disease is caused by the fungus puccinia striformis tritici, which can overwinter in Alberta. The greatest risk is from airborne spores carried from wheat producing regions in the United States.
The spores produce fungal strands, which grow beneath the leaf surface and re-emerge within 10 days as a raised orange or yellow stripe on the surface of the leaf.
In good conditions, the fungus consumes the leaf and the released spores re-infect other portions of the plant and ultimately the entire crop. In the end, the field takes on an orange shade prior to the release of trillions of spores onto nearby crops.
Once leaves lose their photosynthetic capacity, the grain fills poorly and shrivelled kernels result in yield reductions as high as 30 percent. Stripe rust also reduces grain quality by lowering test weight.
Lethbridge centre manager Brian Freeze confirms the American connection with stripe rust.
“Satellite imagery technology the last few weeks has identified up to 64 storm events where we expect that particulate matter from U.S.,” said Freeze. “Rust areas has been transferred into the Lethbridge area. This last couple of days of storms in southern Alberta have been of particular concern.”
“We have found it in our Lethbridge research plots and in some fields,” said Freeze. “Given that a major dumping of rust spores has occurred in southern Alberta, it only takes about 11 days for spores on infected fields to develop and then spread. If spores are allowed to develop, they will likely spread into the Peace River Country and into Saskatchewan.
“If the disease can be controlled here, then spread into other areas can be prevented.”
Freeze said current conditions in southern Alberta are ideal for stripe rust. Most of the winter wheat in southern Alberta is AC Bellatrix, which has no rust resistance. Cool wet conditions promote rust development and the cool spring has delayed winter wheat development by two weeks.
Spring wheat can also be affected, he said.
