Steps to Take When Mold is Present in Corn


Step One: Identify and Quantify the Mold(s) Present

It is important to remember that the presence of visible molds is only an indicator and needs to be identified and quantified to determine its potential negative impact.

  • If 10% of the ears have mold present that covers more than 25% of the ear, send in a representative sample for proper identification.
  • Below are examples of Plant Pathology Labs (for identification) in the northern U.S. where you can send samples. Check with your state for the nearest plant pathology lab.

Type and Appearance: Diplodia
Diplodia photo
Description: Initially appears as a white mold beginning at the base of the ear but eventually becomes grayish brown and rots the entire ear. The mold may be apparent on the outside of the husk or on the shank. There may be raised black bumps on the moldy husk or kernels.
Mycotoxin Possible? No. However, even if mycotoxins are not present, feeding and palatability of the grain may still be affected.


Type and Appearance: Gibberella
Gibberella photo
Description: Develops as a red or pink mold that almost always begins at the tip of the ear. The silks and husks may stick to the ear due to mold growth. In severe cases, the pink mold is visible on the outside of the husks at the ear tip. The fungus produces the mycotoxin vomitoxin.
Mycotoxin Possible? Yes


Type and Appearance: Fusarium
Fusarium photo
Description: Symptoms include a white to pink, cottony mold that can begin anywhere on the ear but often begins with insect-damaged or split kernels. Usually the entire ear is not rotted and affected kernels are scattered across the ear. Infected kernels are usually tan or brown or have white streaks. The fungus produces the mycotoxin fumonisin.
Mycotoxin Possible? Yes


Type and Appearance: Aspergillus
Aspergillus photo
Description: Appears as a grayish-green powdery mold that may begin at the tip of the ear or follow insect injury tracks. Infected kernels are brownish, lightweight and shrunken. The fungus produces the mycotoxin aflatoxin.
Mycotoxin Possible? Yes


Type and Appearance: Penicillium
Penicillium photo
Description: Green or blue-green powdery mold that occurs between the kernels usually at the ear tip. Infected kernels can appear bleached or streaked.
Mycotoxin Possible? Yes


Type and Appearance: Cladosporium
Cladosporium photo
Description: Dark green or black powdery mold that also causes black streaks on kernels. It usually forms first where kernels are attached to the cob.
Mycotoxin Possible? No. However, even if mycotoxins are not present, feeding and palatability of the grain may still be affected.


Type and Appearance: Trichoderma
Trichoderma photo
Description: Dark green mold that grows on or between kernels and often covers the entire ear. This disease typically is not economically damaging because it only occurs on scattered ears.
Mycotoxin Possible? No. However, even if mycotoxins are not present, feeding and palatability of the grain may still be affected.

 

Step Two: Contact Crop Insurance Agent

There are provisions within some policies to cover low test weight, kernel damage and other quality issues. It is important to contact your crop insurance agent immediately if there might be a plant disease that will affect grain quality.

 

Step Three: Detect if Mycotoxins are Present, then Identify and Quantify

If the mold detected in step 1 is greater than 10,000 cfu/gram and is of the Aspergillus, Fusarium, Gibberella or Penicillium strains, then a mycotoxin screening should be completed.

  • Contact your crop insurance agent. In this situation, samples must be pulled from the field by a loss adjuster prior to the grain being placed into storage. Penicillium toxins may not be covered under the policy, so check with your agent.

  • Either you or a loss adjuster will need to send in a representative sample for proper mycotoxin screening (examples below). Check with your agent for the proper procedure. Check with your state for the nearest diagnostic lab.

    • Veterinary Diagnostic Lab, North Dakota State University
      • 174 Van ES Hall, Fargo, N.D. 58105 | Phone (701) 231-8307
    • Veterinary Diagnostic Labs, Iowa State University,
      • 1600 South 16th Street, Ames, Iowa 50011 | Phone(515) 294-1950
    • FOR PENICILLIUM: Trilogy Labs,
      • 870 Vossbrink Dr., Washington, Mo. 63090 | Phone: (636) 239-1521

 

Step Four: Harvest and Storage Management Strategies

Dry Grain

Harvesting

  • Harvest and dry the grain in a continuous flow dryer to a moisture level of 14% and then cool to ambient air temperature as quickly as possible.

    • Plenum temperatures should range from 190-210 F for this crop to qualify as useable.

Storing

  • Begin the cool-down process as soon as your grain goes into storage.

    • A 60,000 bushel bin with a 20 hp fan at 4" static pressure will give 1/3 CFM of air.
    • It will take 3 days of operation to reduce grain temperatures by 10 degrees.
    • Ultimately grain should be cooled to 30-35 F for safe storage. As outside air temperatures start to go down, cool the grain as quickly as possible.

Monitoring

  • Stored grain should be evaluated weekly until sold.

    • One person should access the bin by the manhole using the ladder and another person at the lower level should start the fan letting it run 3-5 minutes.
    • Have the person on the top level check the air quality in the bin to make sure there is no condensation, that the air is fresh and cool and that the static pressure gauge stays at the same reading as the previous week.

Marketing

  • Once the crop that has experienced plant disease issues has been properly harvested and stored, prospective buyers should be contacted to determine how they want to evaluate the marketability of the crop.

 
 
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