Aflaguard® For Aflatoxin Control
DR. DON HERSHMAN
LEXINGTON KY. PRINCETON, KY.
The current dry conditions across much of
western Kentucky has some producers
concerned about potential aflatoxin
problems. Aflatoxin is a natural toxin and
carcinogen produced in corn (and other
crops) infected by the fungus Aspergillus
flavus. Aflatoxin contamination in food and
feed is regulated by the U.S. Food and Drug
Administration (http://www.ca. uky.edu/agc/pubs/id/id59/id59.pdf).
When preharvest aflatoxin contamination
occurs in corn, it is most often associated
with drought and high temperatures, especially
during grain fill. Damage to the kernels
increases the risk of contamination.
A novel product called Aflaguard® is being
marketed for reducing aflatoxin contamination
in corn and peanuts. It consists of nonviable
barley seed coated with spores of a
naturally occurring strain of A. flavus which
is atoxigenic. This means that this organism
does not produce aflatoxin. It is thought to
otherwise behave like toxin-producing
strains of A. flavus, outnumbering the native,
toxin-producing strains and displacing them
within the ear of corn. This helps to reduce
preharvest contamination. This approach is
used successfully for aflatoxin control in cottonseed
using another product, AF 36, which
is a different atoxigenic strain of A. flavus.
Dr. Tom Isakeit of Texas AgriLife Extension
has evaluated Aflaguard® in replicated, randomized
field trials, a challenging task for
something as complex as this issue. His research
thus far shows that, as expected, Aflaguard
® often (though not always) reduces
aflatoxin contamination in corn. His studies,
done in a year of severe drought, show that
these reductions sometimes result in an economic
benefit through a reduced discount on
the harvested grain, though sometimes not,
particularly when contamination levels are
low. Dr. Isakeit is continuing to test the product
under commercial conditions, under
varying levels of aflatoxin pressure.
Reducing mycotoxin contamination through
the use of a biocontrol agent in the field is biologically
a very difficult challenge, yet Aflaguard
® often provides measurable and
significant reductions in aflatoxin contamination.
To a microbiologist like me, this is really
impressive. However, there are several
complications in deciding where the product
fits.
• The product should be applied before tasseling
for optimal benefit, but aflatoxin contamination
in Kentucky is often affected by
the conditions that occur after silking.
• The majority of Kentucky corn fields that
experience heat and drought during grain fill
generally don’t develop significant aflatoxin
contamination, so widespread use may not
make economic sense. And if contamination
potential is high, not even Aflaguard® can
bring down levels to make it safe for human
consumption.
• The atoxigenic strain requires moisture to be
activated to produce spores. Application of the
product during drought conditions can result in
control failure.
Thus, if a producer is concerned about the
risk of aflatoxin contamination, application
of Aflaguard® prior to silking may help reduce
anxiety, and that may be enough justification
to use it. Plus, the product may sometimes
improve marketability of the grain. However,
I don’t foresee widespread use of the product
in Kentucky, even under the drought conditions
we have seen this growing season.
Thanks to Tom Isakeit, Texas AgriLife Extension,
for reviewing a draft of this article.
Δ
DR. PAUL VINCELLI: Extension Professor
and Provost’s Distinguished Service Professor,
University of Kentucky
DR. DON HERSHMAN: Extension Plant
Pathologist, University of Kentucky