Monday, January 10, 2022

USA Pacific Northwest First Stripe Rust Forecast for 2022

On an annual basis Dr. Xianming Chen, Research Plant Pathologist, USDA-ARS, Washington State University, issues stripe rust risk forecasts for the upcoming season (https://www.wawg.org/first-stripe-rust-forecast-of-2022-calls-for-moderate-levels/).  Initially these are based on weather data from November and December of each year.  Based on November and December 2021 weather data, for the 2022 growing season susceptible varieties are forecast to have a moderate risk of stripe rust.  Potential yield losses for these susceptible varieties can range from 25-40%, and thus may require an initial fungicide application at a herbicide timing.  In contrast, moderately resistant to resistant varieties are forecast to have a lower stripe rust risk and will likely not need fungicide application in 2022.  Further updates from Dr. Chen will be shared as they become available.  

Forecasts from Dr. Chen can then be followed up with the Prairie Crop Disease Monitoring Network (PCDMN) weekly cereal rust risk forecasts that are issued from mid-May to early July of each growing season.  These forecasts are based on: 1) the occurrence and severity of rust (leaf, stripe and stem rust) epidemics for source locations in the USA; 2) the occurrence and frequency of wind trajectories that can carry asexual rust spores from source USA locations into at risk Prairie regions; 3) Prairie weather conditions that favour deposition of rust spores and subsequent cereal plant infection and disease development; and 4) the growth stage of cereal crops. 

Background information on the PCDMN cereal rust risk forecasts can be found at: 

https://drive.google.com/file/d/18qX7IbXL40nYpKjLKhJVdwHa0m8Y7-RY/view?usp=sharing

Weekly PCDMN rust risk forecasts can be found at:

 https://prairiecropdisease.blogspot.com/p/cereal-rust-risk-report.html.

If you are planning for the 2022 Prairie growing season and are concerned about cereal rust risk, a foundational strategy to consider is growing a variety with the best level of rust resistance available in the cereal variety you want to grow.  Unfortunately, if the variety you are interested in is rust susceptible then you may need to consider in-crop fungicide application depending on risk.  The PCDMN rust risk forecasts can help to identify Prairie regions where the rust risk is moderate to high, and where further in-crop scouting is required to determine whether a fungicide may be needed.