This article originally appeared in http://cropwatch.unl.edu written by Dr. Tamra Jackson-Ziems, UNL Extension Plant Pathologist.
Drought and high temperatures promote development of the disease Aspergillus ear rot (pictured right). The fungi that cause this disease (most commonly, Aspergillus flavus) can produce aflatoxin. Aflatoxin is one of many chemicals in a group known as mycotoxins that are produced by fungi (molds). Mycotoxins, such as aflatoxin, can be toxic to animal and human consumers and, at certain concentrations, can lead to dockage or rejection of grain at elevators.The unusually high temperatures and drought this summer are having severe impacts on Nebraska corn. In addition to reductions in test weight and overall yield, secondary problems are developing in some corn fields as a result of these conditions.
Corn harvested for grain to this point has been predominantly from fields that sustained substantial drought damage leading to early maturation and plant death. Notable aflatoxin contamination appears to be in a small percentage of southeast Nebraska fields, based on samples submitted to several laboratories in the area.
Mycotoxins are common and can be safely consumed at low concentrations. The concentration of aflatoxin that is considered safe for consumption depends on the age and species of the consumer. An abbreviated summary listing the Action Levels identified by the FDA for aflatoxin is listed in Table below.
Testing for Aflatoxin: Farmers and crop consultants can scout high risk fields for Aspergillus ear rot as an indicator for aflatoxin, but only lab testing of grain samples can accurately identify the concentrations of aflatoxin in the grain. Accurate lab test results for aflatoxin will depend greatly on the quality of the sample that is collected and the laboratory methods used to test it. The test results are only applicable to the sample that is submitted, so it is very important to collect an adequate sample for the best results. Refer to the publication, Sampling and Analyzing Feed for Fungal (Mold) Toxins (Mycotoxins) for recommendations on how to collect and submit a high quality sample for mycotoxin analysis.
Contact and submit samples to a laboratory that is certified by the federal Grain Inspection Service and Grain Inspection, Packers, and Stockyards Administration (GIPSA) for mycotoxin analysis for the most accurate results. A GIPSA website lists laboratories certified to conduct testing in Nebraska. They include
- Lincoln Inspection Service, Inc.;
- Fremont Grain Inspection Department, Inc.;
- Omaha Grain Inspection Service, Inc; and the
- Sioux City Inspection and Weighing service Company.
Some grain elevators and individuals may be using a black light (ultraviolet light) to detect for fluorescence as a method for rapid screening of grain samples. This practice is NOT recommended when making decisions about aflatoxin contamination in loads of grain. The component that produces fluorescence under black light is called kojic acid. Although kojic acid is produced by the same fungus that produces aflatoxin, its presence is not necessarily an indicator of aflatoxin and might lead to false positive results and unnecessary rejection of grain.
High Risk Factors for Aflatoxin Contamination in Corn
- Drought-damaged fields, including rainfed (dryland) fields and non-irrigated pivot corners
- Fields or areas with higher incidence of corn ear-feeding insects, such as the corn ear worm
- Grain damaged before or during harvest or after harvest while in storage
Ear rot diseases and aflatoxin are not evenly distributed across fields or in the grain, so scouting and/or sampling should include a substantial portion, at least several acres. The presence of the fungus in kernels does not always correlate well with the presence of aflatoxin, nor does the absence of visible fungal growth necessarily indicate the absence of aflatoxin.Scouting For Aspergillus Ear Rot
- Open husks to view a large number of ears.
- Look for the presence of dusty yellow-green to olive-green spores, especially on the surface of damaged kernels or ear tips (Figure above).
- Pay special attention to higher risk areas.
Harvest and Storage: If fields have documented Aspergillus ear rot and/or risk of aflatoxin contamination, it is recommended that you harvest and keep grain separate from other grain at less risk, such as irrigated fields. Storage of affected grain is not recommended because ear rot diseases and mycotoxins can continue to accumulate during storage. If storage is necessary, cooling and drying grain to less than 15% moisture within 48 hours of harvest will help to slow fungal growth and aflatoxin production. Grain intended to be stored for longer periods of time should be dried to less than 13% moisture.
Presently, it is too early in the harvest to know the extent of aflatoxin contamination in this year’s corn crop, but at this time only a small percentage appears to be affected.
Resources: For more information, refer to the list of publications below or view this week’s episode of Market Journal.
- Plant Disease Profiles #3: Ear Rot Diseases and Grain Molds, EC1901
- Understanding Fungal (Mold) Toxins (Mycotoxins), G1513
- Sampling and Analyzing Feed for Fungal (Mold) Toxins (Mycotoxins), G1515
- Use of Feed Contaminated with Fungal (Mold) Toxins (Mycotoxins), G1514
- Aspergillus Ear Rot and Aflatoxin Production, Iowa State University Integrated Crop Management News
- Check Cornfields for Aspergillus Ear Rot, University of Illinois the Bulletin
|Table 1: FDA action levels for aflatoxin contamination in corn intended for livestock.|
|Commodity Action Level||(ppb)|
|Finishing (feedlot) beef cattle||300|
|Finishing swine of 100 pounds or greater||200|
|Breeding beef cattle, breeding swine, or mature poultry||100|
|Immature animals and dairy cattle||20|
|For animal species or uses not otherwise specified, or when the intended use is not known||20|
|Source: FDA Action Levels for Aflatoxin|
A few weeks ago I shared some thoughts with you regarding what I learned from an animal welfare conference. We have an opportunity to hear more in at a much closer location-Sutton Community Center in Sutton-on March 12th at 6:00 p.m. Dewey Lienemann, UNL Extension Educator will be presenting on “Protecting Nebraska Agriculture” following a meal sponsored by the Sutton Chamber of Commerce Ag Committee as well as area Cattlemen Associations, Breeders & Feeders, and Ag Producer groups. Anyone interested is invited to attend-and I would encourage anyone who possibly can to attend. This topic not only affects livestock producers, it affects crop producers, and consumers as well. It’s very important to understand how various interest groups are attacking animal agriculture and why and how we in rural America can share our stories. Please pre-register by contacting Tory Duncan at (402) 773-5576 or email@example.com or Todd Mau at (402) 773-5224 or firstname.lastname@example.org.
Another opportunity for learning more about family farm transition is with the last Farmers/Ranchers College program this year. It will be March 15 in Friend at the San Carlos Community Room (next to the Pour House) with meal beginning at 6:00 p.m. (Registration at 5:30 p.m.) The program entitled “Discussing the Undiscussabull” will be presented by Elaine Froese from Manitoba, Canada. Froese’s expertise in helping families get unstuck is sought after across the country. She has worked with families in business for over 20 years and is now coaching the next generation. Elaine believes that change is an opportunity, not a threat…she has practical tools to help people discuss the “undiscussabull” to make their dreams come true. In order to save your spot and reserve a meal, registration is needed by calling the Fillmore County Extension office at (402) 759-3712. The Farmers & Ranchers College is sponsored by area agribusiness, commodity groups in collaboration with the University of Nebraska-Lincoln Extension.
A HUGE thank you to all the Fair Board members, 4-H Council, leaders, youth, parents, volunteers, Clay County News Staff, and Extension staff that made the 2011 Clay County Fair a success! Words can’t really express my appreciation. Driving home every night, I had time to reflect on each day so I decided (for all you farmers) I’d give you a break from irrigation scheduling : ) and provide some reflections from the county fair.
I love watching the fairgrounds come alive…to see the barns and buildings filling up and the excitement of the youth and parents. While it’s a lot of work, I really love fair week and I’ve always appreciated our county fair in Clay County. I appreciate that the focus is on the youth and families-exactly where it should be; we truly have something special here! There was several times in conversation a person this week would say “I haven’t been to the fair in X years” to which I’d respond “Welcome back!”. For those of you reading this and can identify with that statement, I’d really encourage you to come out next year-because you truly are missing out on something special.
Every year different things stand out as I’m sure they do for the youth and parents as well. This year, these are some of my reflections looking back:
*Deanna and Holli working so hard to prepare before fair while Cindy and I continued programming right up to fair. Everything was ready to go and we felt prepared for everything this year!
*The Fair Board Members working so hard before fair, deciding not to run me over before fair : ), and cheerfully picking up trash each morning and doing various tasks throughout fair.
*All the Superintendents, 4-H Council members, and Leaders pitching in wherever needed-how you all organized your volunteers to make the shows, exhibit judging, and the food stand run so smoothly.
*Kurt and Amy-the FFA Advisors from Sutton and Sandy Creek becoming so involved this year-it was great having them as a part of our team!
*The adults and youth who pitched in to clean out horse stalls Wednesday night before the fair.
*The beautiful day for the poultry/rabbit show outside and the youth excited to show their bucket calves and do their interviews on Thursday.
*The family fun night on Thursday night-I love seeing all the families come out and see what the 4-H clubs come up with each year! Games, face painting, campfire, and all the work that went into pre-cutting the wheels and blocks to make small vehicles out of wood-a really cool and fun night!
*Beautiful morning for the hog show and the horse shows running so smoothly.
*The sheep and meat goat judge working so well with the youth –frankly all our judges did a great job with this-it’s where the focus should be-but the sheep/meat goat judge was exceptional!
*The beef judge commenting the quality of our breeding beef can compete with any show anywhere; just watching our youth building their herds for the future with hopes of coming back-that is exciting!
*The awesome buyers at the livestock auction, the excellent job that Bruce McDowell did as always and that Lonnie Stripe did as well, and a smooth-running auction!
*The dedication of the Clay County News staff-especially Tory who endured all the shows in order to capture those special moments and feature stories!
*The way so many swine families stuck around at the end to clean up the swine/sheep barn and help me put things away this year so I didn’t have to do that myself. I really appreciated that!
*There are many moments but for the sake of space, THANK YOU ALL for making the Clay Co. Fair a success!