Southern corn rust is showing up early in south Georgia this year and threatens yields as corn nears tassel.
Dr. Bob Kemerait, University of Georgia Extension plant pathologist, reports two cases of Southern rust found this week in Early County by agent Brian Cresswell near Damascus, Ga., and just below the Echols County, Ga., line in Florida by agent Justin Shealey.
Damascus find is thanks to the cooperative efforts between UGA Extension and our friend Dennis Jones with Pioneer.
Here are Kemerait's points to consider:
“SOUTHERN CORN RUST is early this year. Currently, southern rust likely is a threat to corn across the southern part of Georgia.
Southern corn rust is our most important disease of corn.
Rain is back in the forecast for late this weekend; early next week, which will be favorable for development of rust.
I think that corn that is approaching or has passed the tassel-growth stage is worth protecting if the yield potential is there….. I generally would wait to spray for Southern rust until your crop is approaching tassel.
Triazole fungicides (like tebuconazole) are effective against rust but lack the broader activity against Northern corn leaf blight and have a two week protective window. Strobilurin products and combination strobilurin/triazole of strobilurin/SDHI (Priaxor) have three week protective intervals and also a broader spectrum of activity.
Northern corn leaf blight is generally in check this year."
Also, stink bug populations are increasing in field corn. So especially if you are about to spray a fungicide, check for stink bugs. Mostly brown stink bugs are being found. Browns are harder to kill so the high rate of bifenthrin needs to be used to control them.
We have just harvested wheat and other small grains and stink bugs may be moving out of these areas and tree lines as well into field borders.