Aflatoxin in Corn

Aflatoxin in Corn  By Blair Fannin

WACO – Amid strong commodity prices across all sectors of agriculture lies concerns about aflatoxin by Texas corn growers.  “We don’t have a lot of tools to deal with it,” said Scott Averhoff, president of the Texas Corn Producers Board, addressing grain producers  at the 49th Blackland Income Growth Conference recently.  However,  Averhoff along with industry leaders, administrators, scientists and
specialists with Texas AgriLife Research and the Texas AgriLife  Extension Service, say they are working diligently to find solutions.

Aflatoxin  is a cancer-causing poison produced by the fungus Aspergillus flavus that grows unpredictably in corn during periods of hot and dry weather.  At least $14 million in losses due to corn mycotoxins have been recorded  for Texas corn producers, but the losses to Texas agriculture overall  are likely closer to $200 million, according to AgriLife Extension  economists.  “Research takes time,” said Dr. David Baltensperger, head of Texas  A&M University’s soil and crop sciences department. He said he  understands the
frustrations by Texas corn growers affected by aflatoxin  and asked growers for their patience as research moves forward.  "We are restricted to utilizing our current best management practice for aflatoxin control," he said.  Baltensperger outlined a proposal that would create a regional center for research  and Extension efforts specifically addressing aflatoxin. The center would be comprised of scientists and Extension experts from seven universities throughout the south, and would be in partnership with the  corn producer boards
in each state.  “We want to create awareness at the federal level and second, and  identify pathways through research and extension activities to help  solve this issue,” he said.  Baltensperger said the group will meet  in Birmingham, Ala., this spring to discuss creating the project, but in  the meantime outlined several topics on the agenda with regards to  aflatoxin mitigation:

-  Remediation: This would include using clay binders, which absorb mycotoxins and allow for safe

consumption by livestock. Current rules  are pending in Texas to make this a reality.

-  Biological controls: Baltensperger discussed developing better  biological controls and utilization of those currently available. He  said despite Aflaguard (a biological control agent to control fungi)  being on the market, there needs to be better testing procedures to differentiate corn that has received treatments. Current black-light  technology may show if a fungus is present, but cannot show if the toxin  is present.

-  Breeding: He said currently there is no corn variety completely resistant to aflatoxin, but some accumulate less aflatoxin than others.  “One of the problems we have right now is knowing the relative susceptibility
of a variety to aflatoxin,” Baltensperger said. “It’s not  published by seed companies, but we know there are large differences in  relative susceptibility. We need seed companies to test and market  their most resistant,
well-adapted hybrids and help producers avoid the most susceptible. This requires testing.”

-  Basic genomics: Baltensperger said more work needs to be done in identifying and using traits in corn that might have impact host plant resistance to aflatoxin. Searches for additional aflatoxin-resistant  genes are under way but are difficult, costly and poorly funded. Dr. Seth Murray, AgriLife Research corn breeder, said solving the aflatoxin problem is going to take “an integrated approach.”  “So far, corn host resistance and insect control are a few of the control options, but there’s no silver bullet,” he said.  “You  might be growing Bt corn or something that helps reduce insect problems, and in some areas insects are a vector to the aflatoxin  problem, but in many areas of Texas we see aflatoxin coming through the silks of the plant, with insect control having a minimal effect,” Murray  said.  A majority of the corn hybrids on the market are bred in the Midwest, he said, and they have open-husk features. Spores tend to enter the husk standing upright after a rain event, causing potential for alfatoxin.  “Initially, the most resistant lines and hybrids we have identified yielded poorly and were not well adapted here, while the highest-yielding lines were very susceptible to the toxin,” he said. “As  a breeder I and others combine the best resistance genetics and yield  potential together. We continue to see improved progress every year but  this still takes time and has a substantial cost.”  AgriLife  Research has so far released four lines – Tx772, Tx736, Tx739 and Tx740  – all of which have shown favorable results in resisting aflatoxin. These should be of value to companies as they work to incorporate  improved resistance into their hybrids.  “But  AgriLife Research doesn’t have the capability to put this into hybrids,” he said. “What we need is encouragement from producers to get a
partnership established between AgriLife Research and the seed companies to create a new aflatoxin-resistant variety or varieties.”

For more on AgriLife Research corn breeding activities, visit http://maizeandgenetics.tamu.edu/.