Beer-can Ears Are Nothing to toast
A peculiar form of incomplete kernel set, not widely seen since 1992, has cropped up in parts of Indiana and Ohio in recent weeks, according to Purdue Extension corn specialist Bob Nielsen.
"The phenomenon has been called Stunted Ear Syndrome, Pinched Ear Syndrome, Beer-Can Ear Syndrome, or Pop-Can Ear Syndrome depending on who is describing the problem," Nielsen says.
The corn expert says this mysterious syndrome has symptoms that include normal-looking plants and ear shoots (husk leaves), but cobs as short as several inches. The short cobs have varying degrees of kernel set, and a tasselbranch-like appendage on their tips. Sometimes instead of that appendage, Nielsen says there is the remainder of the tiny ear initial similar to that visible by dissection at about the 9-leaf collar stage.
"Kernel row numbers at the base of these ears appear to be normal or at least acceptable," Nielsen says. "I've seen such ears with 16 to 18 rows of kernels. The problem is, compared to an acceptable 35 to 40 kernels per row, these ears only contain about half that in terms of ovules per row and often only 12 to 16 actual kernels per row."
Nielsen says problem fields don't seem to share the same soil fertility levels, herbicide programs or corn diseases. One similarity, however, is most were planted during the last two weeks of May.
"There are definite variety differences within individual fields, but the extent of the problem can also vary dramatically with the same variety planted from one field to another," he says.
The cause of the Beer-Can Ear Syndrome is unknown, but Nielsen says he believes it reflects a single event that stopped early ear- shoot development.
"I believe the problem occurred some time after the 6-leaf collar stage, when the plants completed development of leaf initials and began development of tassel and ear initials, but not much beyond the 12-leaf collar stage, when potential kernel row numbers were finalized," he says.
Nielsen hopes Indiana and Ohio farmers or others who have seen this happening can help solve the beer-can ear mystery by sending him the information listed below.
"If more than one field or hybrid was affected, please send me information on each circumstance. If you've taken photographs of the problem, send along a few copies," Nielsen asks.
If you have access to the World Wide Web, see this phenomenon at http://www.agry.purdue.edu/agronomy/cornnews/articles.96/p&c9645.htm.
Nielsen asks that the following information be sent to him at Agronomy Dept., Purdue University, West Lafayette, IN 47907-1150 or by Email to firstname.lastname@example.org
* County and State * Approximate percent of * Average length of ears field affected * Any particular part of the * Corn type (normal yellow dent, field affected more than others? white, popcorn, waxy, food-grade) * Seed company and hybrid number * Planting date * Any major nutrient deficiency * Approximate (or actual) soil pH problems in affected areas? of affected and unaffected areas * Post-emergent corn herbicides * Post-emergent corn applied in 1996 (include what and when) insecticides applied in 1996 * Any unusual weather during (include what and when) the first 45 days or so after planting?