2018 Ear Molds in Corn

Ear molds in corn can impact both yield and grain quality. Many of the molds that impact grain can also create toxins in the grain, which may impact marketing the crop. Livestock producers and ethanol plants can be especially sensitive to the impact of toxins in regard to feed quality and animal consumption. Toxins should be evaluated individually to assess potential issues.

Elements of Disease

There are three elements of the disease triangle that must be present to have expression of disease in your crop.

  1. Individual hybrid sensitivity (host).
  2. Disease presence.
  3. A supportive environment that allows expression of the individual disease.

It is very important to document individual hybrids and fields impacted by the respective ear molds.

Timing of Harvest

Early harvest and drying grain to levels that limit further growth of the disease is the only management tool we can use today to impact grain quality. To limit disease growth in storage, corn should be dried to 14.5%.

Future Plans

Reducing the soil inoculum levels with tillage, crop rotation and applying stalk digesters (PCT | Sunrise BioBuild Digester) after harvest, along with fall herbicide programs can help reduce potential for future infections.

2018 Ear Molds in Corn

Fusarium: The most common ear disease we are seeing this fall. Ear symptoms are variable and depends on the corn hybrid and the environment. Individual kernels along the ear that are tan to light brown are typical with Fusarium.

Corn kernels and silks can exhibit whitish-pink growth and a white “starburst” pattern can be seen on the kernels. Infection is most common at the tips of the ear.

Fusarium brings mycotoxins called Fumonisins. These are especially toxic to horses and impact other livestock.

The picture below shows Fusarium white “starburst” on kernel surface. 

Gibberella: We are seeing very little Gibberella this year. Gibberella spores enter the corn via the silk channel. Active moisture and cool temperatures during silking contribute to heavy infection. In 2009, growing conditions heavily favored a high incidence of Gibberella which left many growers to deal with very poor grain quality. Extended moderate temperatures and moist fall weather in 2016 allowed the Gibberella fungus to form even though we didn’t have moisture at silking.

Symptoms of Gibberella include a pink to red growth on the surface of kernels and a pink to white color between kernels which can be noticed on the cob when shelling. If corn is infected early, the disease can cover the entire ear and cause husks to be pasted to the kernels.

The picture below is from 2016. It shows a late season Gibberella infection with growth between kernels and on the cob surface.

Gibberella mycotoxins are primarily identified as Deoxynivalenol, more commonly called DON or Vomitoxin and Zearalenone. DON causes animals to lose appetite, reduce feed consumption and in some cases complete feed refusal.  Zearalenone can cause reproductive issues in animals, especially swine. This is the same fungal disease that causes head scab in wheat. 

Diplodia: We are seeing ample volumes of Diplodia infected ears this fall. This disease is a thick white mold that is typically seen at the bottom of ears and develops upward. Upright ears catch rain and allow it to pool at the base which helps launch the infection. The husk will appear glued to the ear and discolored.

Kernels are lightweight and often the cob is very spongy and grinds when shelled.

Diplodia strains in the USA do not bring mycotoxins but can be difficult to feed with poor quality and off flavor.  Long term storage is not recommended with this ear mold.

Other Ear Molds

The following ear molds can be found in Ohio but are usually very rare in our geography to have major impact on grain quality.

Penicillium: Usually occurs around damage from birds or insect feeding. Powdery blue/green on and between kernels can be seen. Contains Ochratoxins.

Aspergillus: Yellow/green spores on and in between kernels. Only occurs in extreme drought and high temperatures through the growing season. Contains Aflatoxins.

Impact of Insects

Insect feeding on the kernels and through the husk cover has been shown to increase potential for ear molds and toxins. Above-ground insects are very difficult to predict and difficult to manage outside of in-plant crop technology. 

FDA Feeding Guidelines for impacted Grain (Aflatoxin Level)
Finishing Beef Cattle (300 ppb) (part per billion)
Finishing Swine (200 ppb)
Breeding swine, cattle (100 ppb)
Mature poultry (100 ppb)
Dairy animals (20 ppb)
Immature animals (20 ppb)

FDA Fumonisin guidelines in Animal Feed (Feminism Level)                                 
Horses (5 ppm)
Swine (10 ppm)
Poultry (50 ppm)
Beef Cattle (50 ppm)
Dairy Cattle (no recommendation)

FDA Vomitoxin guidelines in Animal Feed (Vomitoxin Level)
Feedlot Cattle (10 ppm)
Chickens (10 ppm)
Swine (5 ppm)

Note – 1 ppb = .001 ppm

To compare Parts per Million (ppm) to Parts to Billion (ppb)
*1 ppm = 32 seconds in one year
*1 ppb = 3 seconds out of a century

 

Written By: Brian Mitchem, PCT Research Agronomist

October 10, 2018, 10:44 AM
 

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