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Common Corn Diseases – Part 1: Ear Diseases
September 14, 2018

Common Corn Diseases – Part 1: Ear Diseases

There are several common ear and stalk diseases that affect corn every year, and regardless of field, there’s always a risk for disease. As we look forward to harvest, now is the time to identify and plan for proper storage of potentially moldy grain. This is the first of a two-part series that investigates the most common examples of ear and stalk diseases and discusses ways to avoid them.

A Closer Look at Ear Rot

Ear rots can affect grain quality and reduce nutrient values, test weight and yields. In some instances, mycotoxins may be produced, which can negatively affect how well livestock can digest the grain.

Several factors determine the severity of the disease, including:

1.     The presence of the pathogen,

2.     The right environment, and

3.     A susceptible host such as corn 

Many corn hybrids vary in their susceptibility to certain ear rot. Environments such as corn-on-corn and reduced tillage increase the chance and severity of ear diseases showing up this time of year. Other conditions like low fertility, extremely high populations, damage from wind, hail, or tillage, and a tight husk can lead to higher incidence of ear rot. Also, fall rains during harvest time that limit corn drying favor corn ear mold development.

Fusarium Ear Rot:

·       One of the most common types of ear rot

·       Can affect any part of the ear

·       Warm and wet conditions favor disease development and kernel moisture is greater than 20%

·       Enters through wounds from threats like hail, insects, or sand blasting

·       Found in a wide range of corn environments

·       Mold on the ear can be powdery, pink or white in color and may show as a starburst pattern on seed

·       Can produce a mycotoxin that affects how well livestock can digest the corn

·       The fungal pathogen survives on corn residue

Fusarium Ear Rot

 

Diplodia Ear Rot:

·       White mold starting at the base of the ear and will move up as conditions favor growth

·       Ears will have a “mummified” look and lighter test weight

·       Warm and wet conditions favor disease development during grain fill period

·       Is not known to produce mycotoxins

·       Can be recognized by black fungal reproductive structures on the ear and stalk

·       Upright ears and tight husks can lead to higher levels of this disease

·       Corn-on-corn leads to a higher risk of this disease

Diplodia Ear Rot

 

Gibberella Ear Rot:

·       Pink to light pink in color and occurs in the tips of the ears but under favorable conditions can cover the entire ear

·       Infections occur through insects or birds feeding on the ears during silking or up to three weeks after silking

·       Infection occurs during cool, wet weather or extended periods of rain in the fall

·       Can produce mycotoxins that affect grain quality for livestock

Giberrella Ear Rot

 

Pencillium:

·       Powdery blue-green mold that can develop on or between the kernels, usually at the tips caused by wounds to the ear from insect feeding, earworm feeding, or other damage to the ear

·       Warm wet conditions favor the development of this disease

·       This disease can cause storage problems in high-moisture grain in bins

·       To reduce this disease or the damage it can cause, limit wounds to ear caused by insects and store grain at low moistures

Penicillium – On Right Ear, Aspergillus on Left

 

Aspergillus:

·       Green-yellow-olive mold that infects wounded kernels

·       Favored by hot, dry weather during the last half of the growing season, after pollination

·       Drought stress corn can favor higher levels of the pathogen and is most common under 80-100-degrees (F) temperatures with relative humidity levels above 85 percent during and after pollination and grain periods

·       It is capable of producing a mycotoxin

Ways to Reduce Your Risk

To reduce the chance of disease in your corn, avoid planting in corn-on-corn conditions and reduce insect wounds. Also, if your feeding corn to livestock an early harvest and drying the corn may needed to reduce the amount of ear mold development.

Insect wounds can be reduced by planting SmartStax® or VT Double PRO® corn products designed to limit feeding insects. It’s also beneficial to choose B&A Genetics hybrids combined with Protect ‘N Grow Seed Treatment with multiple fungicides to protect against many diseases in the early development of corn. As always, we encourage you to reach out and our team will help you determine the best course of action for your fields.

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