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With dry conditions this season, ways to combat aflatoxin in corn are taking on huge significance.
LSU AgCenter plant breeder Dr. Steve Moore continues to look for ways to combat aflatoxin in corn, especially in evaluating lines for resistance.
He has planted more than 1,500 corn lines obtained from the North American Plant Introduction Station in Ames, Iowa, over a number of years at the LSU AgCenter’s Dean Lee Research Station south of Alexandria. His work, which is funded in part by a grant from the Louisiana Soybean and Grain Research and Promotion Board, is evaluating those lines for resistance to aflatoxin biosynthesis.
Aflatoxin is a byproduct of Aspergillus flavus, a naturally occurring fungus that is found in soil across the southeastern United States and normally is relatively harmless until conditions – such as heat and drought – are right for aflatoxin biosynthesis.
Aflatoxin is a cancer-causing toxin, Moore said.
In his studies, corn ears are inoculated with Aspergillus flavus after silking. After harvest, kernels are ground to a meal and sent to the U.S. Department of Agriculture’s lab at Stoneville, Miss., for aflatoxin analyses.
From the lines he has evaluated, Moore has selected 34 that have shown relatively low aflatoxin production.
"We hope at least one of the lines will show better resistance than the ones currently available to growers," he said. "If so, we will consider the project a big success."
Moore is working in cooperation with research associates Mildred Deloach and Jim Hayes and researcher Dr. Rick Mascagni – with trials being replicated at the LSU AgCenter’s Northeast Research Station in St. Joseph and its Red River Research Station in Bossier City.
Moore said the research objective is to incorporate new genes that provide superior resistance into commercial corn cultivars.
Aflatoxin is a major production concern for corn growers in the region, and although resistant lines have been identified, resistance has not been transferred into commercially useful hybrids at the desired level of performance, Moore stressed.
The last severe aflatoxin outbreak in Louisiana was in 1998 when heat and drought combined to increase the toxin in corn fields.
"If temperatures rise above 95 degrees, we will have to keep an eye on corn this year for aflatoxin contamination, since the crop may already be stressed due to low rainfall," Moore said early this season.
The LSU AgCenter researcher explained that the fungus "loves hot temperatures" and that when conditions are right "it takes off."
But he said a bright spot may be this year’s market conditions.
"If aflatoxin does occur, high corn prices hopefully will help growers absorb the cost of perhaps treating the grain," Moore said.
The LSU AgCenter researcher said glufosinate, a key ingredient in Liberty herbicide, may raise the ammonia level in the corn, which breaks down aflatoxin. But results from field research trials are inconsistent.
Corn lines from field research trials should be harvested in August, and results should be available after aflatoxin concentrations are measured at the USDA’s Stoneville facility.
Moore hesitates to make predictions, but he said he considers this research to be "exciting and important in that the potential exists to identify new and improved resistance."–Mary Ann Van Osdell
(This article was published in the 2008 edition of the Louisiana Soybean & Grain Research & Promotion Board Report.)