Northwest Iowa Crop Update Newsletter by Todd Vagts ISU Extension Crops Specialist Counties Served:  Carroll, Calhoun, Crawford, Ida, Monona, Pocahontas and Sac.
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Volume 2, Number 26

Northwest IA Crop Update, September 26, 2002
(Word Document)

Introduction
Harvest of both corn and soybeans is beginning to pick up across west-central and northwest IA.  Preliminary yields of both crops looks to be promising, even with the many challenges the crop faced throughout the season.  Northwest IA ended the year with an above normal degree-day accumulation, yet it was in-line with last year.  Are your corn hybrids approved for all markets?  If in doubt, contact your seeds-man or visit one of the listed web addresses.  Concern over aflatoxin in corn in west-central and southwest IA has been raised; scout your high risk fields for gray-green or yellow-green molds on grain kernels.

Growing Degree Day Accumulation and Crop Development
Now that most crops have surpassed physiological maturity, it is interesting to look back at the growing season and look at where we picked up excessive degree-days or in some situations fell behind normal.  You can see in Figure 1 that we started out the season rather slow, picking up less than the 11-yr average for N.W. Iowa and much behind 2001.  The area rapidly caught back up from mid June through July.  Temperatures cooled in August with the rainfall (perfect conditions for soybean yield development) but picked up again in early September.  Overall, N.W. Iowa ended up with about 200 degree-days ahead of normal yet was just about exactly the same as last year.

Are you sure your corn grain is approved for export?
Some GMO corn hybrids are approved for human and livestock consumption in the U.S., but NOT for export into other countries.  Be sure you know what markets your GMO corn hybrids are approved for.   Contact your local seeds-man for information or go to this website provided by the National Corn Growers Association (Know Before You Grow) http://www.ncga.com/biotechnology/know_where/index.html  If you need a location to sell your non-export approved grain, visit this website for grain handling facilities that have indicated a willingness to purchase, receive, and handle genetically enhanced corn products that have full U.S. registration for food and feed use, but are not yet approved for import into the European Union.  http://asta.farmprogress.com/locator.htm

New National Web site Focuses on Value Added Agriculture
The Agricultural Marketing Resource Center launched a new Web site to provide education and research to producers about business development and marketing related to value added agriculture.  The new Web site, www.AgMRC.org contains contacts and directories, as well as new business development and commodity-specific information designed to help build successful value added agricultural enterprises. 

Aflatoxin in corn
I’ve taken several calls in the last week about the potential presence of aflatoxin in corn grain, primarily from western Monona county.  Anytime corn experiences extended drought stress conditions and/or insect damage to the ear, there is a risk of Aflatoxin development.  Aflatoxins are a group of chemicals (mycotoxins) produced by certain mold fungi, specifically Aspergillus flavus and Aspergillus parasiticus.  These two fungi can be recognized by gray-green or yellow-green molds on corn kernels in the field or in storage.  But don’t jump to conclusions to quickly; the presence of mold on grain does not necessarily indicate contamination of the grain with Aflatoxins. 

Alfatoxin development:  Most gain mold becomes associated with the kernel in the field, but can also grow and spread in stored grain.  Therefore it is very important to remove high risk corn from the field and dry to 15% moisture as soon as possible.  Extended dry down time in the field or periods of 4-hours or greater of wet corn in wagons or bins greatly increases the chance of mold development.

Detection  Alfatoxin can be detected at elevators with the use of black lights or commercial test kits (immunoassay or ELISA).  The black light is very unreliable, meaning it can give many false positives.  The commercial test kits are much more accurate, but they require a trained person to operate.  If in doubt, send grain samples to an approved lab for testing. (http://www.extension.iastate.edu/Publications/PM1098A.pdf)

Sampling:  Aflatoxins do not occur uniformly in a field or load of grain, therefore the best approach is to make a composite sample consisting of sub samples from every part of a load, bin or unit of corn.

What to do with aflatoxin contaminated corn:  Corn that is contaminated at levels greater than 20 ppb may not be sold for interstate commerce.  Feeding contaminated grain at less than 300 ppb to livestock is the most readily available alternative.  Contaminated corn can be used in Ethanol production.  Aflatoxins do not accumulate in the ethanol but will be concentrated in the co-products which are typically fed to livestock.

Prevention:  Scout early to detect presence in high-risk fields; control insects in the field and in storage; adjust the combine to minimize kernel damage; and separate damaged and moldy kernels from the grain during harvest or when transporting to storage.

For more information on aflatoxins in corn, refer to ISU Extension publication PM-1800
http://www.extension.iastate.edu/Publications/PM1800.pdf125

(Word Document)