Agriculture News: Aflatoxins in corn crop a possibility

By Keenan Bishop Published:

A few weeks ago I mentioned that there were concerns now of aflatoxins in corn that survived the drought. The following comes from Pierce Paul, Plant Pathologist, OSU Extension.

There have been a few reports of Aspergillus ear rot in corn in some parts of Ohio, causing producers to be concerned about possible grain contamination with aflatoxins. Ear rot development does not automatically mean that grain is contaminated with aflatoxins, but provides a good indication that the risk of contamination is high.

So far this year I have had only one confirmed report of aflatoxin contamination in the state. The best way to determine whether you indeed have an aflatoxin problem is to scout fields for Aspergillus ear rot and then send samples to a lab for testing. Below is a list of steps one should take when sampling for ear rot, testing for aflatoxin, and handling suspect grain samples during shipment and storage.

Scouting for Aspergillus ear rot: Walk fields and examine ears from multiple plants at multiple locations. The fact that weather conditions this year have been favorable for Aspergillus ear rot does not automatically mean that you have an ear rot problem. The risk is indeed high, but the level of infection and grain contamination usually varies from field to field, depending of soil type, hybrid susceptibility, and cropping practice. Check for Aspergillus ear rot by stripping back the husks and examining the ears of 80-100 plants from across the entire field for a yellow-green or gray-green mold.

Sampling for aflatoxin: Samples for aflatoxin testing could be collected directly from the field, truck, grain stream, or grain bin. However, regardless of where the sample is being collected, it is important to make sure that it is representative of the entire grain lot. By representative I mean it must be a sample that provides a reasonable estimate of the level of contamination of the entire grain lot and not just one section of the lot.

Toxin contamination is never uniform throughout a grain lot, it is often found in hot spots. Therefore it is extremely important to pull multiple samples from every part of the lot. When sampling from the grain stream, collect samples at regular intervals. Pool and mix the individual samples into one composite sample from which about 5-10 lb. of grain is sent for testing.

Sending samples for aflatoxin testing: Adequate handling of samples is an important part of the aflatoxin testing process. Samples should be dried to 12-14 percent moisture and shipped in cloth or paper package to minimize aflatoxin buildup during shipment and storage.

Testing for aflatoxin:

A) Blacklight or UV light test consists of visually inspecting the grain for the presence of greenish florescent particles under UV light. This test should only be used as an initial screen, since other particles in the sample may also glow, giving a false positive result. On the other hand, the absence of a fluorescent glow does not mean that the grain is not contaminated.

B) Several commercial quick-test kits are available for aflatoxin testing. Unlike the blacklight test, these are specific for aflatoxin. However, several of these tests are only qualitative or semi quantitative, meaning that they tell you whether or not the grain is contaminated or whether the level of contamination is within a certain range, but do not provide precise estimates of the levels of contamination.

C) Analytical laboratory tests, if done correctly by a certified lab, are by far the best for determining aflatoxin contamination. These tests are usually accurate and quantitative, and provide estimates of the exact level of contamination. Grain marketing decisions such as dockage and price discounts should be made based on results from analytical lab tests rather than blacklight or commercial quick tests.

Storage: To minimize further mold development and toxin accumulation in storage, grain should be dried to 15 percent moisture shortly after harvest. Remember, the level of toxin will not decrease in storage, but could increase substantially if storage conditions are favorable for continued fungal growth and mold development.

Aspergillus flavus, the aflatoxin fungus, grows best at 80-90F and 18 percent moisture. Cleaning grain after harvest to remove fines may also contribute to reducing toxin buildup in storage, since broken and cracked kernels often favor the growth of A. flavus.

UPCOMING PROGRAMS

SUPPLEMENTING HAY TO FEE WINTER HERD

Those raising livestock already know that the most expensive part of owning an animal is feeding it through the winter. This winter will be especially tricky since we’re following drought conditions. Pastures were stretched to the max and cattle may be under conditioned going into winter.

Fortunately it sounds like most everybody has adequate hay, but do you know the quality? High corn and commodity prices will make supplementing your hay supply a little tricky this winter.

Once you know the nutrient level of the hay you are feeding plus the requirements of the animals eating it, then you can find out what and how much to supplement with.

Join us this Tuesday for a supper sponsored by your local Southern States and learn about Mol-Mix Liquid Feeds and other feeds in general that are available here. Brett Reese, Southern States Forage Specialist, will be speaking on Ryzup Smartgrass for extending pastures.

Call the office at 695-9035 to sign up.

KSU THIRD THURSDAY THING

Third Thursday Thing this month is this Thursday and is on Fruit and Vegetable Processing and Sorghum starting at 10 with a welcome and then “Sweet Sorghum Processing and Demo” by Michael Bomford, KSU.

Then Angela Anandappa, Program Coordinator, UK Food Systems Innovation Center will discuss “Profitable Processing,” followed by “Home-based Processing and Microprocessing Program” by Debbie Clouthier, UK.

Following lunch is “Safe Food Processing” by Shadrick Adams, Food Manufacturing Supervisor, Kentucky Food Safety Branch. Closing up will be “Pawpaw Processing: How-to and Demonstration” by Sheri Crabtree and Jeremy Lowe, KSU.

For questions contact Dr. Marion Simon, KSU State Specialist for Small Farm and Part-Time Farmers at 597-6437.

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