Stripe Rust Starts Developing in the Pacific Northwest

February 18, 2011
Xianming Chen,
Research Plant Pathologist
Stripe rust of wheat has waked up much earlier this year than last year in the Pacific Northwest and may not have slept in the western Oregon and western Washington. Don Wysocki and Jim Towne found sporulating rust pustules in a wheat field near Pendleton in the northeastern Oregon on the 1st of this month. Last week, Mike Flowers and Chris Mundt reported that stripe rust was easily found (about 5% incidence) in wheat fields in the Willamette Valley of western Oregon.

Yesterday, I stopped by the Horse Heaven Hills in the south-central Washington and found sporulating rust pustules in several wheat fields, even in some fields where plants were still small (5 to 7 leaves without dead leaves) and stripe rust was not found in last November. Rust severity was up to 5% of incidence. The rust has survived the relatively mild winter with help with the widespread snow cover in the cold spell of the first week of last December.

Rust will develop fast when weather gets warm (night temperatures into the 40s F and day temperatures into the 50s F). Considering widespread infection before the winter, early application of fungicides will be better for fields planted with susceptible and moderate susceptible cultivars. Please check your fields when weather in your area reaches the above range and if you see stripe rust, consider spaying with fungicide even before herbicide application. If no rust is found but the planted cultivar is susceptible or moderately susceptible based on last year’s reaction, the field should be sprayed with fungicide when you spray herbicide. Please consider using full rate of fungicide at the time of herbicide application as the rust has already started so early and this rust season will likely be very long.

From Juliet Marshall
U of I Extension Cereals Specialist

Thought we should all know what is transpiring to our west / northwest. See the stripe rust alert below from Dr. Xianming Chen, USDA-ARS, Pullman, WA. While this does not mean we WILL have an early and damaging amount of stripe rust this upcoming season, it does mean we will have increased risk of stripe rust developing. Conditions conducive for disease in wheat will also be conducive for disease in barley, although stripe rust in barley is rare.

We will be constantly monitoring the situation and will release additional alerts as needed. Check our website at

http://www.cals.uidaho.edu/scseidaho/

You can also sign up for email notifications of small grains pest alerts (and other less important crops) at:
Pacific Northwest and Treasure Valley Pest Alert Network

http://www.tvpestalert.net/

Juliet Marshall
Associate Professor, Cereals Pathology and Agronomy
Idaho Falls R&E Center
1776 Science Drive Suite 205
Idaho Falls, ID 83402
208-529-8376 office
208-390-4859 cell

http://www.cals.uidaho.edu/scseidaho/