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The Risk Map below applies to cereals in the most susceptible stages for infection.
For wheat that occurs at flowering (Feekes 10.51).
For barley flowering occurs around head emergence
Check the map below to see the predicted risk for your area of South Dakota.
This map indicates relative risk for scab based on weather data analyzed over the past 7 days and the forecasted weather for up to 3 days .
***Map Updated June 7, 2009** **Disclaimer**
SPECIAL COMMENTARY June 7, 2009
Rain...but scab unlikely to occur in WW
Normally, a weekend of wet weather at heading time might have growers reaching for the phone to call in the air force with fungicides at the ready. But, remember - even though scab likes wet, it likes WARM and wet, and the water should be somewhat continuous for some time before and during heading time. The drizzle and rainfall the last couple of days should not greatly impact our scab outlook in the winter wheat crop. As it is the first real moisture we've seen in many parts of the state since mid-May, and because the temperatures have been hovering around the 40's and 50's, scab is not likely to occur. The cool weather should help our wheat crop to fill out nicely and, hopefully, keep those fungal diseases in check without the need for added input costs of fungicides.
Remember to check back as your fields approach flowering for the latest updates on scab risk in your county.
Just a few notes about scab: the disease is caused by a fungus (Fusarium graminearum) that enjoys warm, wet weather prior to and during flowering. If your crop is near heading or flowering, pay close attention. Cereals planted over corn residue are at somewhat higher risk because of the high levels of inoculum present. Winter wheat often escapes major infection. However some years when growth is delayed due to over-wet soils, or weather is particulary wet through heading/flowering, scab can occur at damaging levels. Check back regularly through mid-July for further developments and updates.
For additional information, go to www.wheatscab.psu.edu - our partner forecasting site.
Click on a date below to view archived risk advisories from earlier in the season:
June 1, 2009 Archived Advisory
May 28, 2009 Archived Advisory
May 26, 2009 Archived Advisory
Legend for Map Colors:
Red High Risk Info Yellow Info Blue Info White Unknown Info
DISCLAIMER:This website and the risk advisory service contained within are offered free of charge to the public. The advisory was developed to provide wheat and barley growers with information to help them make more informed decisions about disease management. It is not intended that the advisory be used solely to schedule fungicide treatment, rather it is intended to aid growers and crop managers in that decision process. Understanding the relationship of weather/enviroment to scab development is one of the keys to implementing sound management strategies. The advisory is only a tool to illustrate the relative risk for scab development. The models used to develop the risk advisory are experimental. Any management decisions made based on the information contained herein are strictly the responsibility of the person or persons making such decisions. No warranty or guarantee is expressed or implied.
Links to return to:
SDSU Extension Plant Pathology Homepage
College of Agriculture & Biological Sciences
SDSU Plant Science Department
This page is maintained by the SDSU Extension Plant Pathology Project, Dr. Lawrence Osborne, Extension Plant Pathologist and Project Leader, SDSU Plant Science Department. ph (605) 688-5543.
Comments or Questions? Please feel free to email: Lawrence Osborne
Last modified: June 7, 2009
