Uniform Cereal Variety Testing Program

Stripe Rust Situation on Zak

June 24, 2002

Stripe rust has been detected on WSU's new spring wheat variety 'Zak'.  Although this line has been rated as having adult plant resistance to stripe rust, Zak is displaying seedling susceptibility to some new races, like Pst 78 that was recently identified in the United States.  Stripe rust is more influenced by night-time rather than day-time temperature.  Even if the day-time high exceeds 90ْF, the spores will survive if the night time temperature is less than 60ْF.  Night time temperatures have been in the 40 ْF range across the region for a majority of the spring crop season, therefore, stripe rust spores are flourishing.  Weather conditions have been ideal for the pathogen this year. 

 Based on current weather conditions, fungicide application may be required to avoid crop losses due to stripe rust infection on Zak this year.  We recommended that a fungicide be used to control the spread of stripe rust on Zak if 10% of the leaf or leaves (any leaf, not just the flag leaf) are infected in 10% or more of the stand. 

 At least two fungicide options are available:

1. Quadris at a rate of 6.2 to 10.8 fl oz product/A
2. Tilt at a rate of 4 fl oz product/A

Please contact us with additional questions or concerns:

Dr. Xianming Chen, USDA-ARS Plant Pathologist

Email: xianming@mail.wsu.edu

Phone: 509-335-8086

Dr. Kim Kidwell, WSU Spring Wheat Breeder and Geneticist

Email: kidwell@mail.wsu.edu

Phone: 509-335-7247