PARMA, Idaho — Stripe rust in wheat has been detected from Eastern Idaho to Eastern Oregon and growers are being advised to check their fields closely for signs of the disease.
The disease, which can cause significant yield and quality losses, has arrived in the region early this year and likely over-wintered here, researchers said.
Stripe rust in wheat typically is blown into Idaho from other states, said Juliet Marshall, University of Idaho cereals extension specialist.
Its presence this early in the season, coupled with symptoms on the lower leaves, is a strong indication that it over-wintered here, she said.
In years with serious stripe rust outbreaks caused by the disease over-wintering, it usually doesn’t spread until after Memorial Day, Marshall said.
“We’re already seeing pretty good infections in both” dryland and irrigated wheat, she said.
Stripe rust has been found in susceptible spring and winter wheat varieties from Bannock County in Eastern Idaho to Malheur County in Eastern Oregon.
Marshall found stripe rust in two Southeast Idaho fields on April 4, one in a commercial field south of Aberdeen and the other in a field of volunteer wheat between Pocatello and American Falls where stripe rust was found in November.
Stripe rust was also reported in a wheat field east of Wendell in Southcentral Idaho in April and it was detected this week in winter wheat nursery plots at UI’s Parma research center in Southwestern Idaho, as well as in fields between Nyssa and Ontario in Oregon.
The fungus proliferates well in the cool, wet conditions prevalent in many areas across Southern Idaho and Eastern Oregon this spring, she added.
“Conditions are good for the fungus this year,” she said. “I’ve been worrying about having a really big outbreak this spring.”
People with susceptible wheat varieties should check their fields weekly and closely, Marshall said. “It’s really critical that people scout for the fungus.”
Stripe rust in wheat has been an intermittent problem in Eastern Oregon and the last two years it arrived late enough in the season that most growers decided not to treat for it, said Bill Buhrig, an Oregon State University Extension cropping systems agent.
But he said there’s concern that its early arrival this year may mean growers will have to spray for it, which costs about $20-25 an acre total.
Stripe rust in barley has also been detected in one field at low levels. Stripe rust in wheat does not cause stripe rust in barley and vice versa, but the detection of both is an indication that conditions are ripe for the fungus, Marshall said.
Marshall encouraged growers to report any occurrence of either wheat or barley stripe rust to her at firstname.lastname@example.org
She strongly recommended growers plant one of the many resistant wheat varieties available, a recommendation seconded by Filer grower Jerry Mai.
“We do grow resistant varieties as much as we can,” he said. “It’s really the only thing we can do. It’s kind of silly not to.”