University of Idaho
HAZELTON, Idaho — The severity of a stripe rust infection detected in a wheat field near Hazelton May 29 indicates a potential larger problem, according to University of Idaho researchers.
“Given the severity of the infection in that field, it probably means we have a high potential for further development of stripe rust,” said UI plant pathologist Juliet Marshall, who reported the find to growers. “It could be much more widespread.”
The plant disease, which can cause losses of up to 60 percent in susceptible varieties, was confirmed in one field of Brundage soft white winter wheat near Hazelton, which is located east of Twin Falls.
Marshall said the field showed heavy and uniform stripe rust infection and researchers are seeing some odd symptoms that may be related to stripe rust in other nearby fields.
“The potential is high for stripe rust to be a big problem” this year, she said.
Marshall said it’s unlikely the plant disease over-wintered in southern Idaho because of the cold temperatures here this winter and it’s likely that recent high winds brought it here from Arizona or northern California.
“If it wasn’t for the high winds, we probably wouldn’t have seen this,” she said.
According to an alert sent to growers by Marshall, winter wheat planted early last year is starting to head or past flowering in southern Idaho and yields are still vulnerable right now.
It recommends spraying a field if it shows 5-10 percent stripe rust infection, unless the wheat variety is 90-95 percent resistant.
“If you have a susceptible variety, you better by spraying,” Marshall said.
According to the alert, most of the wheat and barley varieties in this area will have adult plant resistance, which will help prevent major losses, but fewer varieties will have seedling resistance.
Spraying is highly recommended if a spring wheat field shows 5-10 percent infection.
According to the alert, “susceptible crops with high yield potential, especially irrigated crops, should be at the top of the priority list for spraying.”
It also recommends scouting spring wheat aggressively because “the earlier the infection, the greater the potential loss. Look for early infection on the lower leaves.”
Idaho Grain Producers Association Executive Director Travis Jones said the disease is a concern but the industry is fortunate to have the researchers and chemicals available to combat it.
“Be very aware of what’s going on in your fields,” he said. “We’re always concerned about any type of disease like that that can affect production but there are ways to treat it.”