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College of Food, Agricultural, and Environmental Sciences


Ohio's Drought Causing Stunted Corn Ears

September 18, 2007

COLUMBUS, Ohio – This season's drought may be the cause of stunted ears being found throughout Ohio's cornfields. The abnormalities may pose harvest challenges for growers and potentially impact yields.

Peter Thomison, an Ohio State University Extension agronomist, said that ear stunting is nothing new, but the problem is more widespread than usual due to the hot, dry conditions that have plagued much of the state.

"When you experience a hot, dry growing season, it's not unusual to see more small, misshapen ears on corn due to the effects of drought stress," said Thomison, who also holds an Ohio Agricultural Research and Development Center appointment. "However, we are also seeing ear abnormalities on corn plants that look otherwise healthy and were relatively unaffected by drought. These ear abnormalities are characterized by varying degrees of ear stunting, a problem known as 'arrested ear development.'"

Stunted ear development has been associated with several factors, including environmental stress, certain genetics and pre-tassel chemical applications. Ear stunting may also be related to a temperature shock resulting from a major fluctuation in temperatures during stages of early ear formation.

"University agronomists in other states, including Illinois, Indiana and Pennsylvania, are tracking the same issues we are seeing here in Ohio. Stunted ears are normally an oddity and usually relegated to limited areas within fields, but the problem this year seems more widespread than normal, although it's still highly localized," said Thomison. "If growers just have pockets of fields with abnormal ears, then yield impact may be negligible, but widespread problems could mean major yield losses. In extraordinary situations, when you have a high percentage of plants with ear stunting with only 100 kernels or less on the ear as opposed to 500 to 600 kernels per ear across entire fields, you could easily be looking at a 50 percent to 60 percent yield loss."

Thomison warns that these abnormal ears may be difficult to harvest because of small irregular sizes. He recommends farmers make combine adjustments where needed.

Corn ear abnormalities being found in fields include drought damaged ears, also known as "nubbin" ears; multiple ears syndrome, also referred to as "bouquet" ears; and blunt ear syndrome, most commonly referred to as "beer can" or "pop can" ears.

Nubbin ears are small, misshaped ears with poor kernel set, especially at the ear tip. Bouquet ears are characterized by multiple ears on the same ear shank. Sometimes ears associated with this multiple ear syndrome show ear stunting with some ears devoid of kernels due to late silk emergence and lack of pollen. Beer can ears are markedly reduced in size and kernel numbers and are sometimes associated with multiple ear syndrome.

"Plants with stunted ears will turn red or purple because there is no place for the sugar to go and it will just accumulate in the leaves," said Thomison.

Despite the issues with abnormal ear development, Ohio's corn is drying down quickly, and some fields will be ready for harvest this week. According to the Ohio Agricultural Statistics Service, 32 percent of the crop is mature, ahead of the five-year average.

The U.S. Department of Agriculture is forecasting an average of 150 bushels per acre, up 7 bushels from August, but 9 bushels below last year's record of 159 bushels per acre. However, if production of 567 million bushels is realized, the crop would be the largest ever produced in the state. Growers are expected to harvest 3.78 million acres for grain this year, 820,000 acres more than in 2006.

Candace Pollock
Peter Thomison