Plant pathologist at the LSU AgCenter Trey Price said, "Some years we see it. Some years we don't.
Price said a moderate to heavy infestation has been found in a fungicide trial at the LSU AgCenter Dean Lee Research and Extension Center in Alexandria and in commercial fields in southwest and south central Louisiana. Lighter disease levels have been observed in northern Louisiana.
The potential yield losses in late-planted corn could be significant enough to be critical with this year's low prices.
Price said corn planted in mid-to-late April is more susceptible to the disease. If corn is in the milk to dough stage right now, you should be scouting for it.
He said variety trials at the Dean Lee Center may help reveal which hybrids have resistance. Fungicides may help reduce the effects - if an infected crop has yet to reach the dent stage - with strobilurin and triazole fungicides having activity. After the dent stage, he said, fungicides likely will not provide an economic benefit.
Fungicide applications, if warranted in late-planted corn, will slow disease development and preserve yield.
The disease infects leaves and interferes with photosynthesis, resulting in reduced yield from decreased kernel development. The disease usually starts on lower leaves and spreads upward.
Price said unlike common rust disease, the orange spores are usually only found on the tops of leaves and common rust spores are more reddish. He also said warm, humid conditions with consistent rainfall are ideal for Southern rust.
The start of corn harvest is three to six weeks away.
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