College Station, Texas, USA
July 14, 2010
The war against aflatoxin continues. Texas AgriLife Research scientists showcased promising hybrid corn varieties to a group of producers and industry representatives recently at field trials near College Station.
Aflatoxin is a poison produced by a fungus that grows 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 are likely closer to $200 million, said Dr. Seth Murray, AgriLife Research corn breeder.
Murray and members of the project team said they were optimistic about the work they’ve done, giving the group a firsthand look at the at the AgriLife Research/Texas AgriLife Extension Service field trials in the Brazos bottom.
"The main areas where aflatoxin has been a problem is in south central and the eastern part of Texas," Murray told the group.
Breeding corn varieties that fend off the aflatoxin threat is complicated, Murray said. Factors to consider are yield, husk coverage and maturity traits, such as kernel hardness and earworm resistance.
"Numerous traits are controlled by numerous genes," he said. "The only way to pyramid these genes is to crossbreed and cross-pollinate with the goal of developing varieties better adapted to Texas."
Dr. Tom Isakeit, AgriLife Extension plant pathologist, gave an overview of inoculation techniques used in the breeding nursery to more effectively evaluate aflatoxin resistance.
Methods include injecting spores of the fungus into a wound in the side of the ear, or injecting spores through the tip of the ear, without wounding. Another experimental method used in trials is to spread kernels of infected corn onto the ground during flowering.
Corn from the breeding nursery trials is evaluated for aflatoxin by a chemical test or with Near Infrared Spectroscopy, Isakeit said.
He discussed program research to fight aflatoxin. One commercial product, Aflaguard, has had mixed results in his trials. Aflaguard consists of spores of a non-toxic fungus that prevent infection of the corn by the toxic strains.
The treatment led to a 42 percent reduction in aflatoxin on one small-scale experiment. But in a larger experiment, it did not seem to have any effect, Isakeit said.
Dr. Wenwei Xu, AgriLife Research corn breeder from Lubbock, also discussed his program work.
"We're trying to improve drought tolerance and make it less attractive for insect populations," Wu said. "Another area of study is improving irrigation, reducing the amount of water needed annually to irrigate corn crops."
Among the varieties showcased, a line labeled S2B73BC crossed with a University of North Carolina line (NC300) featured genes that were 25 percent tropical and with deep-rooted system.
"This line has featured excellent drought tolerance and low aflatoxin," said Kerry Mayfield, research associate. "It has a good root, goes really deep into the soil, which helps the plant stand up tall and will not blow over. This also helps the ears from falling over on the ground and getting wet."
Another line, B5C X NC300, was developed for silage, also making it a prime candidate for the biomass industry, Murray said.
"It’s a very good line that has done well throughout the U.S.," he told the group. "It has excellent silage yield and is 50 percent tropical with good root growth."
For more information about the research program, visit http://maizeandgenetics.tamu.edu/.
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