Corn Growers – Don’t Let Aflatoxin Ruin Your 2008 Corn Harvest
PORTAGEVILLE, MO.
Corn harvest will begin in the upper Mississippi
delta region by late August, and I
want to warn corn farmers to take precautions
to avoid aflatoxin. Farmers in this region
have not had serious problems with aflatoxin
since 1998, but the problem could occur again.
Here is the situation. The problem occurs
when a mold called Aspergillus flavus produces
this toxin as it grows on corn kernels that have
stress cracks due to drought and/or damage
due to ear worm feeding. The cracks and ear
worm feeding sites provide the mold access to
the starch inside the kernel. The mold feeds on
this starch and produces the toxin. Aflatoxin is
a poison to humans and animals, and grain
buyers will reject truck loads of corn containing
20 parts per billion or more aflatoxin.
This mold can grow on corn kernels in the
field, and it grows rapidly on kernels in storage.
The mold prefers to grow on wet (18-20 percent
moisture) corn kernels at around 85° F. To reduce
the risk of aflatoxin, farmers should dry
freshly harvested corn to 15 percent moisture
within 24 hours of harvest.
I suggest that farmers first harvest some corn
in the corners of center pivot irrigated fields or
harvest some of their dryland corn and have it
tested for aflatoxin. If it is not contaminated with
aflatoxin then the rest of the irrigated corn will
probably not be contaminated.
Corn farmers that irrigated their corn this year
and planted Bt varieties will experience fewer
problems with aflatoxin than others. This is because
the kernels from irrigated corn will have
fewer stress cracks due to drought and will have
less injury from ear worm. Bt varieties are not
resistant to ear worm but will experience less ear
worm feeding injury.
Again, corn farmers should beware of this
problem and always dry their corn to 15 percent
moisture within 24 hours of harvest.
Following these suggested procedures will give
corn farmers a better chance of producing aflatoxin-
free corn during 2008. For more information,
you may call me at 573-379-5431 or visit
the web at
http://aes.missouri.edu/delta/croppest/aflacorn.stm. Δ