From Dr. Bob Kemerait:

Southern corn rust was found in Madison Co. FL yesterday just south of the Georgia line. Established in 2 fields of corn; relatively new. With approaching weather this weekend, I advise growers in Deep South Central and deep Southeast Georgia to consider a fungicide application in their corn nearing tassel or beyond. Early arrival and perfect weather. I hate to spend money unnecessarily but I respect this disease.”

Southern rust pustules occurring on top of leaf blade, Madison Co, FL.

So do we need to start fungicide applications here in Crisp? It may still be too early, based on our distance away from the FL line, though here’s some things to consider from Bob:

  1. Growers who are not scouting can follow our reports on the spread of the disease and determine when risk is “great enough” to spray.
  2. Fungicides like Tebuconazole and other single mode of action products are generally “OK” for control of rust, but don’t have as long of a protective window.  I am not real high on propiconazole, but other singe-mode of action products are “ok” for rust.  When you use products with mixed modes of actions, e.g. triazoles + strobilurins, or traizoles + strobilurings + SDHIs, or SDHIs + strobilurins, you increase efficacy, broad spectrum activity and protective windows.
  3. Fungicides ALWAYS work better preventatively, though ones mentioned above have some curative activity.  Applying a GOOD fungicide when rust is just getting established in a field can be effective.  But without careful scouting, most growers won’t see the rust until it is too late.

In response to 1) please view this corn rust map which is updated in real time: When the disease shows up in GA I’ll let y’all know and as it approaches us in Crisp I’ll shout. If I can help with the decision to spray, let me know.

In response to 3) let me know if you’d like me to come scout a field and I’d be happy to walk the rows.

Thanks for your time.

Best Wishes,

Joshua Grant


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