SALEM — At an extension wheat and seed production meeting here Jan. 6, Oregon State University plant pathologist Chris Mundt issued an alert to Willamette Valley wheat producers to keep an eye out for stripe rust.
Mundt said mild winter weather is creating an ideal environment for the fungal disease to get a foothold early this year. And, he said, “The largest field losses occur when stripe rust starts early.
“You don’t want the rust to get ahead of you,” he said.
Stripe rust and Septoria are the two biggest disease threats to wheat production in the Willamette Valley, Mundt said.
Mild winter temperatures increase the likelihood the rust pathogen survives the winter and shortens the time it takes for the pathogen to complete a generation, which can increase the amount of inoculum in the environment at any one time, Mundt said.
With temperatures 5 degrees above normal in December, and with January starting out with abnormally high temperatures, Mundt said he believes growers could start seeing stripe rust two and three weeks earlier than normal.
“I think this could be a year where it might be possible for stripe rust to start to pop out on susceptible varieties even in mid-January,” he said.
“Let us know if you see something pop up early, because you really need to control disease on a valley-wide basis and we want to know when that first rust is popping up,” he said.
The good news for growers, Mundt said, is that because 2014 was a mild rust year, not a lot of rust inoculum was present in the valley going into the winter.
But, he said, “On the negative side, probably the biggest driver of whether you are going to have a severe stripe rust outbreak is whether or not you had a mild winter.”
Also on the plus side of the ledger, wheat varieties available today are more resistant to rust than varieties available in the past, Mundt said, including in 2011, a year in which rust played havoc with wheat production in the valley.
Mundt singled out the varieties Bobtail and Rosalyn as “very resistant” to stripe rust.
Even given their high level of resistance, however, Mundt advised growers to keep an eye on their fields.
“You really can’t predict how these varieties are going to hold up,” he said.
Mundt identified Kaseberg, SY Ovation and LCS Art Deco as moderately resistant varieties.
“In a low rust year, they are probably going to hold up well,” he said, “so if there is not a lot of rust around, you are probably home free in terms of rust spraying. On the other hand, if there is a lot of rust in the valley, you probably want to give them a treatment.”
Mundt identified the varieties Goetze, Tubbs 06 and Mary as highly susceptible to the disease.
“If you’ve even heard about rust anywhere in the valley, you probably want to give them a treatment,” he said.