Mycotoxins and Aflatoxins Resource Page

Chad Lee, Extension Agronomist, University of Kentucky

Trichoderma.
Photo: Paul Vincelli

Mycotoxins, and specifically, aflatoxins are a concern in corn this fall. There are some reports of harvested loads of corn being rejected because of high levels of mycotoxins.

There are a lot resources to discuss sampling, testing and feeding of corn with mycotoxins. We have put those items together into the Drought 2012 page on the Grain Crops Extension website.

Some of the highlighted links are listed below as well:

• Aflatoxins in corn, ID-159
• Laboratories that Test for Mycotoxin Analysis
• Commercially Avaialable Test Kits for Mycotoxin Detection
• Scouting corn for Aspergillus Ear Rot
• Fusarium ear rot and fumonisins
• Fumonisin, Vomitoxin, and Other Mycotxins... ID-121
• Aflatoxins in Corn, Oct. 20, 2010
• Harvesting and Storing Kentucky's 2012 Corn Crop
• Effect of Mycotoxins on Swine (Univ. of Minnesota)
• Mycotoxins in Feeds: CVM's Perspective (FDA)
• Mycotoxin and Dairy Cattle
• Utilization of Weather-Stressed Feedstuffs in Swine Diets
• Mycotoxins and Swine Performance

Fusarium Ear Rot and Fumonisons

Paul Vincelli, Extension Plant Pathologist, University of Kentucky

Figure 1. Typical symptoms of Fusarium ear and kernel rot.
Note whitish fungal growth.
 Usually damage from Fusarium ear rot affects
scattered kernels or groups of kernels, as shown here.

The content of this article previously occurred in the Kentucky Pest News, number 1315.

Pre-harvest contamination of corn with fumonisins is a possibility in some lots of this year’s Kentucky corn crop. Fumonisins are a family of mycotoxins produced by the fungus that causes Fusarium ear rot. These natural toxins have the potential to cause lethal diseases of horses and swine (the diseases are equine luekoencephalomalacia and porcine pulmonary edema, respectively). Pre-harvest contamination of corn by fumonisins is most often associated with drought stress at the silking stage, a stress that occurred widely in Kentucky and beyond.

Scouting Corn for Aspergillus Ear Rot

Paul Vincelli, Extension Plant Pathologist, University of Kentucky

Fig. 1 Aspergillus ear rot, 
from University of Illinois

The content of this article previously occurred in the Kentucky Pest News, number 1315.

Aflatoxins are potent, naturally occurring toxins that sometimes develop in corn and certain other crops. Aflatoxins are also among the most carcinogenic substances known. There are well-defined limits on how much aflatoxin is allowable in corn, based on the intended end use. For example, corn intended for human consumption must have less than 20 ppb (parts-per-billion!). More information on aflatoxin can be found in the UK Extension publication, Aflatoxins in Corn, ID-59, at http://www.ca.uky.edu/agc/pubs/id/id59/id59.pdf.

Watch for Gibberella Ear Rot in Corn

Paul Vincelli, Plant Pathology, University of Kentucky

Last month, I wrote an article about Diplodia ear rot, our most common corn ear rot in Kentucky. Diplodia has no known associations with mycotoxins in corn. Gibberella ear rot is associated with mycotoxins and in some cases may look very similar to Diplodia. Normally, Gibberella ear rot is not a widespread problem in Kentucky, but this is not a normal year.

Gibberella ear rot is caused by Fusarium graminearum, the very same fungus that causes head scab of wheat. Normally Gibberella ear rot can be a problem in northern state, but in Kentucky, we generally see very little of this disease. I am hearing of reports of epidemics of Gibberella ear rot in central and even southern areas of neighboring states to our north. Again, that doesn’t seem surprising, given the cool, wet weather generally experienced post-silking in many fields.

Storing Diplodia Ear Rot-Affected Corn

Paul Vincelli, Plant Pathology

Diplodia ear rot (DER) is being reported rather widely this year. Questions have arisen about storage of DER-affected corn. The fungus that causes DER won’t develop further if moisture content is below the normal target of 15.5%. However, rotted kernels are damaged kernels, and since the grain integrity is compromised, other fungi more tolerant of low moisture will have an easier time growing. Our agricultural engineers recommend drying damaged corn an extra 0.5 to 1.0 point of moisture for better storability and cooling it as quickly as possible. Producers should make sure to keep that grain well aerated and dry, and market it sooner rather than later.

Fortunately, there are no known mycotoxins produced by the strains of the DER fungus found in North America. In addition to several recent Kentucky Pest News articles on this subject, more information on this disease is available in a UK Extension publication available at http://www.ca.uky.edu/agc/pubs/ppa/ppa43/ppa43.pdf.