Southern Corn Rust in Clinch, Grady Counties

Southern corn rust is confirmed in Clinch Co and Grady Co.

Growers who have sprayed a fungicide with mixed mode of action should get about 3 weeks of control. Will there be a need for a grower to spray a second time? Hopefully not but factors such as a) proximity to confirmed rust find, b) time since last application, and c) time remaining until hard-dough stage must be considered.

FROM JUNE 6TH POST:

1. Growers not at tassel can certainly wait for a fungicide application.
2. Growers at tassel or silking or pollinating stages can wait to make a fungicide application until southern rust is more of a threat (that is when we find it…).
3. SOME corn growers do not want to take the risk of a) the first find of southern rust being missed OR b) having to scramble to make a fungicide application and hire a plane when everyone around them wants to spray also.  These farmers will often decide to spray now. I can’t disagree with their logic.
4. Under current “lower risk” situation, use of a single mode of action triazole like Tilt of Domark or Tebuconazole is less expensive, generally appropriate, and will have a protective window of about 2 weeks.  These fungicides are fair to good on southern rust, but less effective against northern and southern corn leaf blights.
5. Under current “lower risk” situation, use of mixed products, ANY product that mixes a triazole + strobilurin, or triazole + SDHI, or SDHI + Strobilurin, or triazole + strobilurin + SDHI will provide 3 weeks of protection, better activity against rust, and better activity against corn leaf blights, but will be more expensive.
6. WHEN southern rust is a clear and present threat, choice of TOP fungicides for control (Things like Trivapro, Headline AMP, Veltyma, and others) becomes prudent.