Corn Growers – Don’t Let Aflatoxin Ruin Your 2010 Corn Harvest
PORTAGEVILLE, MO.
Corn harvest will soon
begin in the upper Mississippi
delta region, and
I want to warn farmers to take
precautions to minimize aflatoxin
contamination of their
grain. Farmers in this region
have not had serious problems
with aflatoxin since
1998; there have been a few isolated problems
but not region wide. Unfortunately, problems
with aflatoxin contaminated corn may develop
this year because drought and earworm injury
were greater this year that in recent years, and
damage to corn by these especially in combination
can enhance the development of the mold
on corn kernels that produces aflatoxin. All corn
farmers even those that irrigated their crop and
sprayed for earworm or planted varieties with
resistance to earworm should take some precautions
to avoid problems with aflatoxin.
Here is the situation. The problem occurs
when a mold named Aspergillus flavus feeds on
the starch inside corn kernels and produces
aflatoxin. This mold gains access to the starch
through openings in the kernel hull due to
drought caused stress cracks and injury due to
ear worm feeding. I don’t know the reason this
mold produces aflatoxin as it feeds, but it does.
Aflatoxin will be produced as long as the mold
feeds and more will be produced when the mold
grows rapidly.
Aflatoxin is a poison to humans and animals,
and the U. S. Food and Drug Administration designed
methods to protect us and animals from
contaminated corn and corn products. One of
the methods designed by FDA to protect us is to
prevent grain merchants from buying corn containing
20 parts per billion or more aflatoxin.
This is good because it minimizes availability of
aflatoxin contaminated products that we eat
such as corn meal.
This mold can grow on corn kernels in the
field and on corn kernels stored in a truck or
grain tank. The mold prefers to grow on 18-20
percent moisture corn kernels at around 85° F.
It grows slowly on 15 percent moisture corn and
will not grow or grows very slowly on 13 percent
moisture corn. To reduce growth of this mold
and aflatoxin production on stored corn, farmers
should dry freshly harvested corn to 15 percent
moisture within 24 hours of harvest.
Farmers should dry corn to 13 percent for long
term storage to stop growth of the mold and
aflatoxin production.
What should farmers do this year? I suggest
they first harvest some dryland corn and have
the grain tested for aflatoxin. If it is not contaminated
with aflatoxin, then the irrigated corn
will probably not be contaminated. If the dryland
corn is contaminated, farmers should then
harvest some irrigated corn and test it for aflatoxin.
If the irrigated corn has no aflatoxin,
farmers should first harvest and sell the healthy
corn or store it in separate bins and then harvest
the contaminated corn and store it separate
from the healthy corn. Don’t blend
contaminated and toxin free corn in a truck or
grain bin because this may result in contamination
of the entire truck load or bin of corn.
What should farmers do in the future to avoid
aflatoxin problems? I suggest they only plant
corn in fields that can be irrigated and treat
growing corn for earworm if necessary. They
may also consider planting corn varieties resistant
to earworm such as SmartStax,
YieldGard VT Triple PRO, or YieldGard VT PRO.
Again, corn farmers should beware of this
problem and always dry corn to 15 percent
moisture within 24 hours of harvest. More information
is available on the web athttp://extension.missouri.edu/publications /DisplayPub.aspx?P=G4155.
Following these suggested procedures will give
corn farmers a better chance of producing aflatoxin-
free corn during 2010. For more information,
you may call me at 573-379-5431 or
visit the web at
http://aes.missouri.edu/delta/croppest/alfacorn.stm
corn.stm.
DR. ALLEN WRATHER: Professor/Plant Pathology,
University of Missouri