By Tracy Turner, Purdue University
Recent rains in some parts of Ohio might not be enough to thwart the damage from high temperatures and drought conditions during corn pollination, an Ohio State University Extension specialist says.
Pollination, happening now, is the stage in corn development most sensitive to such stress conditions, said Peter Thomison, an OSU Extension agronomist.
Severe drought stress before and during pollination could cause a delay in silk emergence. If the delay lasts long enough, little or no pollen is available for fertilization when the silks finally appear, he said.
"When such delays in silking are lengthy, varying degrees of barrenness will result," Thomison said. "This year it's likely that silk emergence will be delayed in many drought-stressed corn fields unless we get some significant rain very soon."
Thomison, who is also a professor in Ohio State's Department of Horticulture and Crop Science, said the drought might be the major headline of the 2012 corn crop. Already, most of Ohio is experiencing moderate drought, with one section in the northwest area of the state near the Indiana border experiencing severe drought as of July 3, according to the U.S. Drought Monitor.
Temperatures have reached more than 100 degrees in many parts of the state, with heat index values reaching upwards of 109 in many areas.
Corn can shut down pollination when it gets too hot and dry, Thomison said, noting that corn will instead try to shed pollen during the cooler periods of the day "before it gets blistering hot."
"Corn growers are worried about the potential for yield loss and whether there will be enough grain to feed their animals," Thomison said.
Growers are also dealing with the impact of recent storms that hit the region. While many farmers in parts of the state that saw pockets of heavy rainfall cheered the rain, many are also dealing with storm damage as a result of the hurricane-force winds in some cases, he said.
"The storms have been localized, kind of like a shot gun blast in that some areas were getting rain but others weren't," Thomison said. "The violent winds associated with the storms have also caused root lodging in some plants and green snap in others, with breakage below the ears, creating plants that won't produce grain.
"These storms have come with a cost: hail and wind damage. You've got a lot of farmers who are keeping their fingers crossed right now."
Growers who want to check the success or failure of pollination can simply wait until the developing kernels appear as watery blisters, which usually occur some 10 days after fertilization.