WSU Changes Stripe Rust Recommendations

Over the past two weeks, Washington State University crews have been touring the state, looking for stripe rust.  School officials say so far stripe rust has only been found in WSU disease monitoring and germplasm screening fields in various locations except those around Pullman.  On April 9th, crew found stripe rust in the winter crop nursery at Walla Walla.  That field was then re-checked on April 17th, and he crop reached Freekes 6-7. Stripe rust was easy to find in the border rows planted with the susceptible check, and the rust incidence reached 5%.  Compared to this time of last year, stripe rust has not reached the last year’s severity level at this location.  Commercial fields in the area were checked but stripe rust was not found.

Two weeks ago, WSU crews found stripe rust in the school’s winter crop nursery at Lind, and the incidence was higher than the same time of last year.  On April 15th, WSU crews were checking the winter wheat field in Lincoln County, Washington, where stripe rust was reported in November, but was not found during this most recent check.

On April 15th and 16th, stripe rust data was collected on winter nurseries in Mt. Vernon in Skagit County.  Stripe rust there reached to 70% severity on susceptible entries, as severe as usual for this location in western Washington.

On April 17th, crews checked the winter wheat monitoring nursery in Hermiston, OR, and found stripe rust.  It appears that the rust had just started.

On April 17th, WSU reported that stripe rust was found in the winter crop nurseries in the Central Ferry area.  Winter wheat reached Feekes 7-8 and barley to Feekes 10. Stripe rust was "easy" to find on susceptible checks, and the incidence and severity were higher than those of last year at this location.

Again, on April 17th, crews checked the winter wheat nurseries at the Palouse Conservation Field Station near Pullman and did not see any rust.  Lat year, stripe rust was easy to see in the first week of April. For the Palouse region, stripe rust normally starts in the first week of May.

In the eastern Pacific Northwest, stripe rust started relatively late compared to last year, but the disease can develop to an epidemic considering the high moisture so far and favorable forecast weather (both temperature and precipitation) in the next several weeks.  Based on the current stripe rust situation and the new prediction, WSU's recommendations have changed from those issued in early March.  Fungicide applications are recommended for winter wheat fields planted with susceptible and moderately susceptible varieties (stripe rust ratings 6 to 9) before flowering.

For spring wheat, for growers that have not planted, WSU asks that you choose resistant or moderately resistant varieties (stripe rust ratings 1 – 4).  For fields planted with susceptible (stripe rust rating 8 and 9) or moderately susceptible (stripe rust ratings 6 and 7) varieties, please consider fungicide application at the time of herbicide application.  It is always recommended for growers to check fields often.  If you see active rust or rust incidence or severity reaches 5%, apply fungicides as soon as possible.

Stripe rust in the country So far, stripe rust has been reported in Louisiana, Texas, Georgia, Washington, and Oregon.  Compared to last year, stripe rust has been relatively low nationwide, but the disease can develop quickly under favorable weather conditions.  Growers should check their wheat fields for signs of stripe rust and apply fungicides when needed, following recommendations in your region.

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