Extension Ag Update
November/December 2003
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“LOOK LOW AS YOU GO”: A Plan for Scouting Fields and Submitting Samples for Soybean Rust Diagnosis  

While in soybean fields, carefully look at the lower quarter of soybean plants in addition to “top growth”; be sure to examine undersides of leaves.

  • When scouting, randomly look at the lower quarter of 20 plants. Examine the underside of leaves for pustules.
  • If you see something that looks “suspect” for soybean rust – follow this simple protocol:
    • Collect 20 leaflets with suspect symptoms.
    • Leaflets should be flat, dry, and placed between dry paper towels.
    • Leaflets should be packaged in two layers in zip lock plastic bags.
    • The bags should be clearly labeled with a permanent marker providing: date, host plant, collector’s name, phone number, collection location within the field, location of the field, county, township & section, and nearest intersection. GPS information is helpful if available.
    • Immediately submit samples to a University of Illinois Extension office for Distance Diagnostics through Digital Imaging (DDDI). If the sample cannot be immediately shipped, keep refrigerated until shipment to reduce plant deterioration.
    • DDDI sites are maintained at your local/primary Extension unit office.
    • The results of your soybean rust prescreening via DDDI should be available within a few hours.
    • If the DDDI prescreening appears suspect, your plant sample will be submitted via overnight mail to the U of I Plant Clinic.
    • Following confirmation of soybean rust in your area, scout soybean fields using the same protocol and sample submission procedures. Consider evaluating 5 plants in each of 20 locations within a field. If soybean rust is detected and confirmed, fungicides should generally be applied as soon as possible.

For the most current information check the USDA Soybean Rust Information website at http://www.usda.gov/soybeanrust/. The USDA Soybean Rust Observation website at http://sbrusa.net/, shows the location of sentinel plots to monitor soybean rust and also where there are confirmations of rust during the growing season. The Illinois Soybean Rust webpage is at http://soyrust.cropsci.uiuc.edu/index.cfm.