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Shield your corn from aflatoxin threats.

Agronomy Bulletin 63 ─ Aflatoxins

Situation

Dry summers and relentless pests increase your corn crop’s susceptibility to aflatoxins, which are harmful to livestock. Reduce your exposure with effective management.

Factors to Consider

  • Aflatoxin development
  • Testing
  • harvesting
  • FDA action levels
  • Reducing plant stress
Prior to harvest, survey select ears of corn for molds, especially if growing conditions have been stressful.

Action Plan

  1. Understand aflatoxin development. Aflatoxin is a category of mycotoxin that is produced by the mold fungi Aspergillus flavus and Aspergillus parasiticus. Both feed on starch inside corn kernels, typically entering the kernel due to drought stress, stifling humidity, insect feeding and more. Although aflatoxins do not always develop when these mold fungi are present, the risk is much greater.
  2. Identify potential problems early. Prior to harvest, examine fields for ear molds, especially if stress conditions have been ripe for aflatoxin development. If you observe considerable ear mold development, talk with your local agronomist about sample testing.
  3. Sample and test accordingly. While the concentration of mold fungi in individual kernels may be very high, the number of kernels actually infected may be low. A “black light” test that illuminates the fungi’s yellow-green fluorescence is a suitable preliminary exam. If high pre-aflatoxin fungi levels are found, obtain a more accurate diagnosis with a test available from a chemical supply company or deliver samples to an approved chemical testing laboratory.
  4. Leverage best harvest practices. For suspected aflatoxin fields, harvest corn as quickly as possible. Within 24 to 48 hours, artificially dry corn to less than 15 percent moisture content to reduce the risk of continued aflatoxin development. Temperature is another important factor. Cooling the grain below 55 F will slow fungal growth. Store over the long term at 30 to 40 F. Before, during and after harvest, clean all bins and grain handling devices to reduce the risk of further contamination. Also, properly adjust combines and other harvest equipment to reduce further kernel damage that may lead to the spread of disease.
  5. Adhere to government regulations. The Food and Drug Administration (FDA) has a threshold of 20 parts per billion for aflatoxin-contaminated corn, which can be reached with one contaminated kernel in a 5-pound sample. The FDA’s guidelines are measures established to protect consumers and livestock, and they depend on the corn’s intended use. Growers that do not adhere to the guidelines expose their operation to action from federal agencies.
  6. Manage with purpose. Effective agronomic practices will reduce plant stress, lessening the potential for aflatoxin development. Plant at an optimum date, spacing plant populations effectively and choose hybrids protected with SmartStax&#174;, which helps control earworm feeding. Proper fertilization, weed control and pest control will help to lower stress.

Summary

Drought and insects increase stress in corn and can lead to destructive aflatoxins. Managing plant stress, monitoring for molds and using harvest and storage best practices will greatly protect your crop. For more information, contact your local Mycogen Seeds customer agronomist or trusted agronomic adviser.

Published on Monday, August 25, 2014