Aflatoxin data for this year’s corn crop in Kansas and Nebraska show varying levels of the chemical depending on crop location, an expert in the diagnosis and management of field crop diseases says.
Doug Jardine is a professor in the plant pathology department at Kansas State University. In an email interview, he explained what inspection reports reveal about aflatoxin levels in those two states.
Is a higher concentration of aflatoxin being reported in corn this year than in recent years as a result of the drought?
I don’t have data from most other states except for Nebraska. Here in Kansas, levels are similar to 2011. A summary out the Kansas Grain Inspection Service, LLC office in Wichita yields the following information:
- 25% of submitted samples are testing either at zero or below the limit of detection for some tests (<5 ppb).
- 38% of the samples are below the 20 ppb level set by FDA as deemed to be safe for human consumption.
- 80% of the samples are below 100 ppb. At this level, it is safe to feed to mature poultry, breeding swine and cattle and market swine and cattle and sheep.
- Only 9% of the samples tested over 300 ppb, the level for which there is no safe use.
- The company does not report specific levels above 400 ppb. 3% of the samples fall in to this category.
What I cannot determine from this data set is how many would be over 500 ppb, which is the level at which blending can no longer be used as a means to deal with the problem.
What states have been hit hardest by aflatoxin, and which states have experienced the least?
I don’t have individual state data other than Nebraska and what has been recently reported out of Michigan. In visiting with colleagues, I would say that corn growing south of U.S. Hwy 36 is going to have higher levels of aflatoxin than corn grown north of that line.
In Nebraska, 42% of almost 2,000 samples had no detectable aflatoxin. 79% of the samples had levels < 20 ppb and more than 99% of the samples were < 100 ppb. You can see the problem was much less in Nebraska, which is north of Hwy 36.
To what degree were extension specialists and other experts able to predict the levels of aflatoxin being reported this year?
It is difficult to predict specific levels of incidence and severity. I did state last year that if 2012 was as dry as 2011, the problem would be equal or worse than 2011.
While the incidence was about the same, actual aflatoxin levels may have been slightly lower in 2012 due to the extremely rapid drydown of the corn. Once corn is dried to moisture levels below 15%, aflatoxin production ceases.
What are your projections for the 2013 corn crop as it relates to aflatoxin levels? What precautions, if any, can producers take?
More drought will equal more aflatoxin. Use of Bt corn where the Bt event is expressed in the ear is an important management practice since insects can carry Aspergillus spores on their body directly in to the ear and kernels damaged by their feeding will be more susceptible to infection.
Crop rotation, adequate fertilization, burial of crop debris and irrigation or other moisture conserving practices can all help reduce aflatoxin problems, but will not eliminate them completely.