Agronomy Update



As harvest is in full swing in Indiana, growers are coming across a number of issues as they are shelling corn. These issues are unsettling in a year that many growers are calling a disappointing corn harvest. Coffee shop talk has yields ranging from below whole farm averages where the growing season, in particular grain fill, was too wet or too dry, to just above whole farm averages where the growing season was seemingly perfect. Across Indiana though, most growers are experiencing some of the same challenges as the harvest season ensues. Many are claiming this to be “The Year of the Molds” while some are claiming it to be “The Year of the Worms,” and some unfortunate growers are calling it both.

Regardless of what you’re calling it on your farm, these agronomic issues should be noted. A change in harvest schedule and crop planning for the following years may need a changeup. Given varying environmental conditions, some of the common challenges that farmers are reporting have included ear rots, stalk rots, sprouting ears, or weak shanks. Wet conditions occurring during drydown has created an environment favorable for various diseases. Fields damaged by insect pressure such as corn ear worm and western bean cutworm can also increase the potential for ear rots to set in. All of the above issues can cause yield loss, and in some cases, cause significant grain quality loss. Below are some management tips on dealing with potential ear or stalk issues during harvest.

Correctly identifying the ear mold is important in order to understand your risk potential for grain marketing and/or livestock feeding. Some ear molds are capable of producing mycotoxins. To help identify the disease, consider the conditions the crop was planted into, the field history, and the environmental conditions at tasseling, silking, and pollination. Please see the table below (Table 1) for assistance in identifying ear molds.

Table 1. Common Ear Molds in Corn
Disease Diplodia Gibberella Cladosporium Fusarium Aspergillus
Ideal Environment Warm, moist conditions during silking Cool, moist conditions during silking Cool, moist conditions and damaged ear Hot, dry conditions and damaged ear Hot, dry conditions and damaged ear, especially during pollination
Husk Type Most Susceptible Loose Tight Loose Loose N/A
Mycotoxin Potential No Yes No Yes Yes
For more in-depth information on specific ear rots and management visit:
U.S Corn Pathologists Ear Rot Fact Sheet or Agronomy Bulletin 4- Ear Molds in Corn

Once you have determined ear rot exists, and you have diagnosed which ear rot you have, it is time to develop an action plan. The U.S. Food and Drug Administration (FDA) has established the levels of mycotoxins allowed in corn, so grain elevators actively test for mycotoxins. Minimizing mycotoxins at harvest time is important. If you are seeing 30 percent or more ears showing signs of being infected with rots that have the ability to produce mycotoxins likeGibberella and Fusarium, grain testing for mycotoxins is advised.

Harvest infected fields as soon as possible and dry the corn to 15 percent moisture. Store infected grain in temperatures less than 55 degrees to reduce the spread and growth of the fungus. Once harvested, it is advised to keep the infected grain separate from non-infected grain to avoid contamination. Avoid long term grain storage if possible, and move the grain through the appropriate channels immediately.

If long term storage is necessary, it is advised to dry the grain to 13 percent moisture or less. If the grain will be feed to livestock, test for mycotoxin levels before feeding.

For more information on mycotoxins and sampling visit these links: Mycotoxin Fact Sheet or Mycotoxin Sampling 

As harvest is progressing and many growers have switched to harvesting soybeans, those corn fields still standing are at further risk of lodging due to stalk rots. Stalk rots such as Anthranose are very prevalent across the corn belt and can cause significant yield loss if infected fields aren’t harvested in a timely fashion. Make sure to scout fields and assess which fields have the highest, or potential, of stalk rot infection. Plan to harvest those fields first to minimize yield loss.

For more information on specific stalk rots visit this link: Stalk Rots or Agronomy Bulletin 52 – Stalk Rots.

Ear drop is an issue that can take place during harvest that is usually caused by a combination of various factors, with weather stress as the biggest reason for ear drop issues. When high temperatures occur while the corn plant is silking, there is a high chance for a weak shank to develop. Most high-yielding hybrids will still make every effort to produce as much grain as possible, filling out the whole ear. This puts more weight on the already weakened shank.

Disease, drought stress, premature death, and insect pressure can also hinder shank strength. Ear drop can vary drastically by planting date, environment, genetics, and other agronomic factors. Ear drop typically won’t happen with specific genetics year-over-year due to the variations in the above factors.

To minimize the risk of ear drop, harvest fields with the highest probability of drop first. Where ear drop is a problem, running the combine head as high as possible and adjusting the combine ground and header speed can help minimize harvest lost by increasing ear retention. With any sort of harvest loss, be sure to have a plan for the next growing season for potential volunteer corn issues.

For more information on ear drop visit this link: Ear Drop 

Ear sprout, also referred to a vivipary, is the premature germination of corn kernels on the ear before harvest.

This is a rare occurrence, but usually takes place when the ear has dried down to 20 percent moisture or less and the ear takes on water while temperatures are still warm. Typically sprouted ears occur when the ears are still upright on the stalk and excess moisture is collected in the husk leaves.

Highly infected fields can have yield loss and extremely poor grain quality. Harvest infected field first, and dry the grain at a higher temperature to prevent further growth of the seedlings. Screening the grain before storage is also encouraged to reduce the amount of damaged grain in the storage bin.

For more information on ear sprouting visit this link: Vivipary 

No two growing season are alike. Each year Mother Nature provides different weather, and each grower farms differently on different soil types in different geographies.

If you are experiencing any of the above issues at harvest, environmental factors played a large hand in affecting the genetics you planted.

Work with your local Mycogen Representative and Commercial Agronomist to help select specific genetics and create a management plan to reduce the risks of the above occurrences in years to come, while at the same time choosing genetics that will give you the best chance of success for optimal yields.

The information and recommendations in this document are presented in good faith and for general information only. The information is believed to be correct as of the date presented. However, neither Dow AgroSciences LLC nor any of its related companies makes any representation or warranty as to the completeness or accuracy of any of the information. The reader assumes the entire risk of relying on the information.

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