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Help Determine What Causes Blunt Ear Syndrome

Bob Neilsen, Corn Agronomist with Purdue University is looking for fields with unusual ear development, particularly Beer Can or Blunt Ear Syndrome.? The following article from Bob describes the symptoms and possible causes as well as where to send the information.

Like the swallows that return to San Juan Capistrano every year, reports of Blunt Ear Syndrome (BES) or Beer Can Ear Syndrome (BCES) have surfaced this past week. This form of arrested ear development was described in Colorado in 1989, was very prevalent across much of the Midwest in 1992, and has occurred in varying frequencies every year since.

The cause of this problem has never been conclusively determined. Some believe the occurrence of BES is associated with high soil pH or low-lying ponded areas of fields or herbicide injury. I personally lean toward the effects of a cold temperature shock during ear size determination that either directly injures ear shoot tissue or alters the hormonal balance within the developing ear shoot (Nielsen, 2001).).

The accompanying images illustrate the classical symptoms associated with BES from a field I visited this past week. The affected ears were located primarily in the first 10 or so rows along the edge of a field and scattered throughout the remainder of the field; primarily in areas relatively lower in elevation than adjacent areas. I have often found BES in lower areas of the field (which would support my cold temperature theory), but I admit that that sometimes BES is restricted primarily to higher elevations within a field.

Ear size of affected ears is usually fairly normal at the base of the cob, but then the cob simply truncates abruptly. A rudimentary ear tip is usually visible at the end of the truncated cob and is reminiscent of what one would find in ear shoots dissected from plants at about the V9 stage of development. This latter symptom suggests to me that the stress that triggers the BES occurs during ear size determination (Neilsen, 2007a).

Plants with severe BES symptoms may turn purplish-red later in the grain filling period as anthocyanin pigments develop in response to the accumulation of photosynthetic sugars in the leaves and stalk because of the paucity of kernels on the cob. The purpling response is similar to that which often develops early in the growing season (Nielsen, 2008).

Figure 1. Blunt Ear Syndrome

Figure 2. Blunt Ear Syndrome

Figure 3. Blunt Ear Syndrome

Figure 4. Blunt Ear Syndrome

If You Find BES-Affected Fields

If you come across fields that exhibit these BES symptoms, please consider submitting some background information on those fields to an on-line database that may eventually help identify common threads among affected fields. The information I would like to receive is summarized below and the on-line database form is located at http://www.zoomerang.com/Survey/?p=WEB22864Y5G52Y. If you would rather send me the information by email, that would be fine also.

• State/Province (location) of the affected field.
• Planting date of the affected field.
• Seed company (e.g., Bob’s Pretty Good Hybrids)
• Hybrid number (e.g., BN2821)
• Approximate percent of field that is affected with BES.
• Approximate percent of ears affected with BES within the affected area.
• Average length (inches) of affected cobs.
• Average number of kernels per row on affected ears.
• Average number of kernel rows on affected ears.
• Soil pH levels of affected field.
• Other soil test information from affected field.
• General location of affected area within field (throughout, field edges, high ground, low ground, etc.).
• Relative soil drainage of affected area (well-drained, poorly drained, etc).
• Herbicides applied this year (product, rates, application times)
• Fungicides applied this year (including seed treatments)

Related References
 

Nielsen, R.L. (Bob). 2001. 'Beer Can' Ear Syndrome - 2001. Corny News Network, Purdue Univ. [On-Line].
Available at http://www.kingcorn.org/news/articles.01/Beer_Cans-0907.html. [URL accessed 8/16/08].

Nielsen, R.L. (Bob). 2003. Blunt Ear Syndrome in Corn. Corny News Network, Purdue Univ. [On-Line].
Available at http://www.kingcorn.org/news/articles.03/BeerCanEars-0812.html. [URL accessed 8/16/08].

Nielsen, RL (Bob). 2004. Arrested Ear Development (Again!). Corny News Network, Purdue Univ. [On-Line]. Available at http://www.kingcorn.org/news/articles.04/BeerCans-0906.html. [URL accessed 8/16/08].

Nielsen, R.L. (Bob). 2007a. Ear Size Determination in Corn. Corny News Network, Purdue Univ. [On-line].
Available at http://www.agry.purdue.edu/ext/corn/news/timeless/EarSize.html. [URL accessed 8/16/08].

Nielsen, R.L. (Bob). 2007b. Symptomology of Arrested Ear Development in Corn. Corny News Network, Purdue Univ. [On-line]. Available at http://www.kingcorn.org/news/articles.07/ArrestedEars-0904.html. [URL accessed 8/16/08].

Nielsen, R.L. (Bob). 2008. Prevalent Purple Plants Possibly Puzzle Producers. Corny News Network, Purdue Univ. [On-line]. Available at http://www.kingcorn.org/news/timeless/PurpleCorn.html. [URL accessed 8/16/08].