Stripe rust overwintered in at least two Alberta locations, and recent wet, cool weather could favour development of the disease in prairie wheat crops.
Michael Harding, a plant pathologist with Alberta Agriculture, said stripe rust development is hard to predict, but current conditions should serve as an alert to watch for the destructive fungus, particularly in winter wheat.
“Because it overwintered here and because we are getting some cooler, wet conditions now and we do have some susceptible winter wheat around southern Alberta, it’s going to be something to watch for,” said Harding.
The disease also overwintered in southern Saskatchewan, he added.
“This is probably one of the earliest years we’ve had reports of overwintering stripe rust because we had such an early spring, so it was April when we were getting reports of stripe rust lesions on wheat.”
Researcher Eric Amundsen found the fungus in winter wheat projects at Lethbridge March 17, and researcher Kequan Xi found it in plots at Olds, Alta., April 8.
Harding said he has not heard of any stripe rust infections reported in farmers’ fields.
Winter wheat is more vulnerable because few resistant varieties are available. Radiant, once the go-to variety to limit stripe rust problems, lost its resistance a few years ago, Harding said.
Many spring wheat varieties also lack resistance, he added.
Stripe rust tends to show up on the Prairies every year, but its degree of damage depends on initial levels of inoculum and weather conditions.
Stripe rust inoculum typically blows in from the Pacific Northwest region of the United States.
The fungus thrives in cool, wet conditions and can cause defoliation and shriveled kernels. It can affect wheat, barley and triticale.
Timely spraying of fungicides can control an outbreak, but management and use of resistant cultivars are preventive tools.
“The key message is, we know it overwintered in Alberta and we know that the conditions are pretty conducive over the last couple of weeks for stripe rust development, so it’s something we should watch out for,” Harding said.