Vomitoxin, also known as Deoxynivalenol (DON), is a
mycotoxin that may be produced in wheat and barley
grain infected by Fusarium head blight (FHB), also
known as head scab or scab.
THE
ISSUE
Fusarium head blight may infect grain heads when wet
weather occurs during the flowering and grain
filling stages of plant development, and given the
wet spring we’ve had so far in 2010, the risk of
vomitoxin showing up in wheat this year is high,
especially in certain parts of Kansas. Vomitoxin
levels too high are unsafe for humans and animals to
consume, requiring elevators to blend and sometimes
reject wheat with excessive vomitoxin levels. In
addition, wheat delivered to an elevator that is
found to be high in vomitoxins may receive extremely
high discounts in price.
Because of this, it is vital that farmers monitor
their fields prior to harvest and then at harvest,
assess their situation and have a plan to deal with
diseased grain BEFORE delivering to the elevator.
CRITICAL CONCENTRATIONS
The
concentrations of vomitoxin in grain are expressed
as parts per million (ppm). One ppm is equivalent
to 1 pound in 1 million pounds, 1 penny in $10,000,
1 minute in two years, or 1 wheat kernel in 80
pounds of wheat. The U.S. Food and Drug
Administration (FDA) has established vomitoxin
advisory levels to provide safe food and feed.
Unlike aflatoxin in corn, vomitoxin is not a known
carcinogen. Furthermore, grain with vomitoxin would
have to be ingested in very high amounts to pose a
health risk to humans, but it can affect flavors in
foods and processing performance. Human food
products are restricted to a 1-ppm level established
by the FDA. This level is considered safe for human
consumption. The food industry often sets standards
that are more restrictive. Vomitoxin causes feed
refusal and poor weight gain in some livestock if
fed above the advisory levels. FDA advisory levels
are as follows:
1 ppm
Finished wheat products, such as flour,
bran and germ, that potentially may be consumed by
humans. The FDA is not stating an advisory level for
wheat intended for milling because normal
manufacturing practices and additional technology
available to millers can substantially reduce DON
levels from those found in the original raw wheat.
Because there is significant variability in
manufacturing processes, an advisory level for raw
wheat is not practical.
10 ppm
Grains and byproducts
(on an 88% dry matter basis) and 30 ppm in
distillers grains and brewers grains (on an 88% dry
matter basis) destined for ruminating beef and
feedlot cattle older than 4 months and ruminating
dairy cattle older than 4 months, with the added
recommendations that the total ration for ruminating
beef and feedlot cattle older than 4 months not
exceed 10ppm DON, and the total ration for
ruminating dairy cattle older than 4 months not
exceed 5 ppm DON. For chickens, 10 ppm DON
with the added recommendation that these ingredients
not exceed 50% of the diet of chickens.
5 ppm
Grains and grain byproducts destined for
swine, providing that these ingredients don’t exceed
20 percent of the diet
5 ppm
Grains and grain byproducts destined for
all other animals, providing that these ingredients
don’t exceed 40 percent of the diet
It’s
important to note that the occurrence of Fusarium
head blight does not automatically mean that
vomitoxins are present, but a high level of scabby
kernels in the harvested grain means they’ll likely
be present. In addition, the level of vomitoxin in
wheat doesn’t necessarily correlate with the level
of physical damage in the grain.
PREDICTING FUSARIUM RISK
Several Universities, including Kansas State have
created a web-based prediction system for assessing
the risk of Fusarium head scab in your area.
The prediction
system summarizes the weather conditions over the
last 7 days and provides a daily estimate of disease
risk. The risk of disease is presented in a
map-based format where colors represent the chance
of a scab epidemic (green = low risk, yellow =
moderate and red = high risk).
(Kansas Fusarium head scab risk as of May 17, 2010)
The
Fusarium head scab
prediction system
website can be found at:
http://www.wheatscab.psu.edu/index.html Then
<click> on the “Risk map tool.”
SIGNUP FOR FUSARIUM/SCAB ALERTS
Farmers can stay
ahead of potential Fusarium Head Blight (scab)
problems by signing up for a “scab alert” system
recently instituted by the U.S. Wheat & Barley Scab
Initiative (USWBSI).
To
signup go to:
http://scabusa.org/fhb_alert.php
VOMITOXIN AND CROP INSURANCE
Producers that carry
multi-peril crop insurance policies may be eligible
for quality loss adjustments if the reason for the
loss in value is due to a covered event such as
excessive precipitation. Remember that it is
imperative that you always report any damage in the
required timeframes and seek advice from your
insurance company before proceeding with harvest or
destruction of the damaged crop.
RMA Links:
1)
July
2009 Press Release regarding the management of wheat
quality losses
July
2009 RMA Press Release
2)
June
2009 Factsheet on testing facilities and salvage
buyers
June 2009 RMA Testing
Factsheet
ADDITIONAL RESOURCES
1)
KSU
Agronomy e-Updates
a.
6/5/2009 contains an excellent article on head scab
in wheat including tips for scouting, storing,
cleaning and feeding infected wheat.
June 2009 KSU eUpdate
b.
5/14/2010 contains articles on the Fusarium risk
prediction system and a way to sign up for “scab
alerts.”
May 2010 KSU eUpdate
2)
North
Dakota State Question and Answer publication.
NDSU Vomitoxin Factsheet
