Thirsty corn: New report says 44 percent of Iowa abnormally dry or worse

What farmers think of this year's growing season depends upon the amount of rain that has fallen on their fields.

In northeast and east-central Iowa, where rain has fallen when needed if not sooner, crops have taken advantage of an exceptionally warm June to stretch their leaves to the sky.

In southeast Iowa, where some farmers have not had measurable rain for three weeks, the corn leaves are rolling up to conserve moisture each morning.

Curt Zingula, who farms northeast of Marion, said his 2016 corn crop, at this stage in the growing season, looks as good as any he has raised.

'It will be showing tassels by the Fourth of July, and the rich, green color is amazing,” said Zingula, a former president of the Linn County Farm Bureau.

The corn grew so fast last week, he said, that its daily progress was obvious.

In sharp contrast, the leaves on Wayne Humphreys' corn in fields near Columbus Junction have been rolling up each day by 10 a.m.

'If you've got to be dry, June is the best month,” said Humphreys, who got his first measurable rain of the month Wednesday morning.

The roots of his corn plants are going deep in pursuit of moisture - a trait that will help them weather dry spells later in the growing season, he said.

Southeast Iowa's arid conditions are reflected in the most recent U.S. Drought Monitor, released Thursday, which rates 44.2 percent of the state as either abnormally dry or in moderate drought - up from 27 percent last week.

Thursday's report marks not only an expansion of the dry area but also a substantial increase in severity.

In the June 14 monitor, all the affected area was rated as abnormally dry. This week's monitor classifies 11.7 percent of the state in the more serious category of moderate drought.

State Climatologist Harry Hillaker said the updated drought monitor does not reflect the heavy rains that fell Wednesday over much of Eastern Iowa.

While those rains brought relief to some dry areas - notably Johnson and Muscatine counties - most of the driest areas were missed again, he said.

'Most people don't realize how abnormally hot June has been” - 4.7 degrees above normal on a statewide basis through Wednesday, he said. If the pace holds, this June will be the warmest since 1933, he added.

Warmer than normal June weather - 4.4 degrees above normal through June 21 in Cedar Rapids - has accelerated corn growth in areas with adequate moisture, according to Iowa State University Extension corn specialist Mark Licht.

In its current stage of development, he said, a cornfield will use the equivalent of about 1/4 inch of rainfall per day.

'That will increase to about half an inch a day in a couple of weeks when pollination is underway,” Licht said.

The mini-drought has damaged yield prospects, according to ISU Extension agronomists working in southeast Iowa.

'The rule of thumb is that for every 12 hours of leaf rolling, you lose about 1 percent of your yield potential,” said Virgil Schmitt, an extension agronomist stationed in Muscatine.

Schmitt said Tuesday that many fields south of Highway 92 had been experiencing leaf rolling for a couple of weeks.

'Last week you could really start to notice the corn leaves starting to roll to help conserve water,” said Rebecca Vittetoe, an extension agronomist in Washington, Iowa.

The rolling reduces the leaf's exposed surface area, reducing water lost through transpiration, she said.

'Yes, we need a drink but not all is lost,” Schmitt said.

With much of the growing season yet to unfold, a return to normal rainfall would enable the stressed corn to realize much its yield potential, he said.