Early indicators point to return of field rust

Early indicators show another substantial infection of stripe rust could hit Whitman County wheat fields this summer.

Dr. Xianming Chen of the USDA’s Agricultural Research Service in Pullman said last week he spotted rust pustules in several wheat fields in the Horse Heaven Hills in south-central Washington.

Steve Van Vleet, WSU Whitman County extension agronomist, said the Horse Heaven Hills fields are a good predictor of what could happen here.

“It’s an indicator because it usually moves from that area up to the Palouse,” said Van Vleet.

Both Van Vleet and Chen said last year’s extensive outbreak left behind a high number of spores in wheat fields.

Chen said the rust infection of 2010 was the most wide-spread on record.

Those spores, said Chen, survived the winter because a blanket of snow protected them from the early December cold snap.

Van Vleet, though, noted that same snow blanket also protected winter wheat from the cold and wind.

“It’s kind of like a trade-off of wheat versus fungus,” he said. “But you can always spray fungus.”

Chen also noted rust has spread from Oregon to Horse Heaven Hills fields that showed no infestation in November inspections.

Chen said rust can develop fast when the weather warms, when night temperatures are in the 40-degree range and day temperatures are into the 50s.

“It could be bad if we get cool temps,” said Van Vleet. “If we have a wet and cool spring, well then we better dang well think about spraying and monitoring like crazy around here.”

Chen said early application of fungicides will be better for fields planted with susceptible and moderately susceptible varieties. He advised spraying a fungicide when herbicide is applied.