Southern corn rust was found and confirmed yesterday (June 6) in two different fields in Wayne County. It means that not only do we have perfect weather for the disease but that southern corn rust is found nearly from one edge of the Coastal Plain to the other and could be anywhere in between.
Thoughts from Dr. Bob Kemerait about the risk for southern corn rust across the Coastal Plain of Georgia continues to increase because of the facts listed below:
A. Southern rust was found so early and at opposite ends of the Coastal Plain.
B. Much of the crop is moving towards (or has reached) tasseling.
C. The current weather conditions (storm and rain) favors infection and spread.
Management of southern rust involves judicious use of fungicides.
A. An inexpensive fungicide like tebuconazole is effective against southern rust, but does not have the broad-spectrum activity or the length of protective-window that strobilurin, SDHI or combination products have. These products cost more, but do have added benefits.
B. I believe that corn should be protected from rust from very early tassel through the dough stage (R6) of development.
C. In a severe year, I have seen as much as an 80 bu/A increase where a fungicide was applied. 25 bu/A is certainly a very reasonable expectation.
Click here to view fungicides listed in the 2016 GA Pest Management Handbook labeled for managing southern corn rust. They are listed on page 63-64.