Northwest wheat farmers should check their fields for stripe rust, as the next two weeks will be “critical,” an expert says.

If stripe rust is present and the crop hasn’t reached the flowering stage, fungicides can be used on winter wheat, Xianming Chen, research plant pathologist for USDA Agricultural Research Services, said in his latest stripe rust report.

“The rust pressure will be higher in the next two weeks,” Chen told the Capital Press. “We expect these two weeks (to be) quite critical for stripe rust management for winter wheat.”

In recent weeks, lower temperatures and rain created good conditions for rust development. Relatively low temperatures, in the 60s and 70s during the day and 40s and 50s at night, are expected.

The occurrence of stripe rust in commercial wheat fields is generally low because farmers mostly plant resistant or moderately resistant varieties, Chen said. Growers sprayed susceptible or moderately susceptible varieties with fungicides at the time of herbicide application.

Chen recommends growers consider crop stage, location, chemical application requirements and yield potential when determining their next steps.

Most chemicals are effective for 30 to 40 days, so a second application may be necessary, Chen said.

Chen recommends farmers apply fungicide if they see active stripe rust on 5% of their fields.

Growers should check the fungicide’s application requirements. Some growing regions are already past the fungicide application window. Some fungicide labels require application 30 to 45 days before harvest, Chen said.

Source: Matthew Weaver, Capital Press