Thursday, May 28, 2015

Wheat Disease Update

Spring and Winter Wheat

1) Stripe rust 

Stripe rust is being reported from a widespread area, including northern Utah, western Idaho, southern Idaho (Twin Falls and Burley / Rupert area) and now eastern Idaho (Newdale and Blackfoot).

All reports so far have been in Brundage soft white winter wheat.

Brundage is very susceptible. If you have not be applying fungicides to this variety up to now, I would consider it infected and treat with a triazole fungicide which has some curative activity.

Strobilurin products may have reduced efficacy on stripe rust if the plants are already infected.

The Pre-Harvest Interval (PHI) has been reached in some winter wheat production at which time it is too late to apply fungicides. Always follow label directions.

Spray appropriate fungicides on susceptible spring wheat varieties at herbicide application.  

2) Barley Yellow Dwarf Virus

Barley yellow dwarf symptoms are re-occurring in infected fields. Expect to see flag leaves with the typical yellow and red “flags”. For more information, see and click on publications to download the BYD bulletin published by the UI. The heavy rains have really helped to mitigate the damage.

3) Russian Wheat Aphids

Russian Wheat Aphids are damaging wheat in several areas - look for white (bleached) stripes on tightly curled leaves, and trapped heads which appear similar to frost damaged heads. We are seeing frost damage (which is the likely cause in the picture below) and RWA damage in wheat. RWA will colonize both wheat and barley.

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