Stripe Rust Update 5/23/2014

Stripe Rust Update, May 23, 2014

Xianming Chen

Wheat Stripe Rust in the Pacific Northwest

On May 21, I was checking fields in the Palouse region including Whitman County of Washington and Latah County of Idaho.   Winter wheat ranged from middle jointing to heading stages (Feekes 7-10.3).  No rust was found in any commercial fields.  Stripe rust developed up to 40% severity in hot spots in artificially inoculated experimental fields around Pullman, WA.  The development of rust in the inoculated fields has been relatively slow as it has been almost two months since inoculation.   In a breeding nursery near Moscow, ID, only one stripe rust pustule of 2 cm was found.

On May 22, we were checking wheat fields in Whitman, Garfield, Columbia, Walla Walla, Benton, and Franklin counties of Washington; and around Pendleton and Hermiston of Umatilla County in Oregon.  Winter wheat ranged from Feekes 7 to flowering (Feekes 10.5).  Spring wheat ranged from early tillering to middle jointing stages (Feekes 2-6).  No rust was found in fields checked in Whitman, Benton and Franklin counties.  Stripe rust developed up to 10% severity with small hot spots of fewer than 10 leaves in breeding nurseries at Central Ferry (Garfield County), which was inoculated in the middle of April.  In a commercial wheat field north of Dayton in Columbia County, two short stripes of stripe rust were found.   We found stripe rust in three commercial fields north of Walla Walla.  In one of the fields appearing to be a mixture of cultivars, stripe rust was relatively easy to found, but still below 1% incidence.  In three fields checked in south of Walla Walla, we did not found rust.  In our nurseries just outside of Walla Walla, where we found the first infected leaf in the late April, stripe rust is now easy to found, but still very low.

Stripe rust was found at very low level in two commercial winter wheat fields along Highway 11 near Milton in Umatilla County, Oregon.  One stripe of rust was found in commercial winter wheat fields near the Pendleton Experimental Station.  At the station we found a few sporulating leaves in a breeding/variety testing nursery.  Similarly, we also found stripe rust in several lines in a breeding nursery at the Hermiston Station, mostly just one or two short stripes, except one line with most leaves infected, but a resistant reaction.  We did not found rust in fields checked in the House Heaven Hills region (Benton County) and between Connell and Kahlotus.

As stripe rust is still low, fungicide application may not be necessary for most winter wheat fields.  For spring wheat, early application of fungicides is generally unnecessary at the time of herbicide application.  Please check fields and may apply fungicides when stripe rust is found.

In the western PNW, stripe rust has developed as usual.  By the end of April, stripe rust had reached 80% severity on susceptible checks of winter wheat, and we took nice first set data for the winter nurseries at Mt. Vernon.

Wheat Stripe Rust in Other States

Wheat stripe rust has been reported in California, Texas, Louisiana, and Arkansas, and generally at low levels.

Barley Stripe Rust

Barley stripe rust has been reported in California and western Oregon, and was found in northwestern Washington.

Other Diseases and Pests

Wheat streak mosaic and cereal leaf beetle was commonly found in the Walla Walla area, but generally at low incidences.  One spot of barley yellow dwarf was found on wheat at Hermiston Experiment Station.