Young corn

After delayed planting due to a wet spring, Iowa farmers are facing further weather challenges this summer. 

Looking at the U.S. drought monitor, it would be hard to guess that excess rain caused problems for growers in eastern Iowa this spring.

At least 12 counties along the eastern third of Iowa are currently classified as abnormally dry based on the Aug. 1 map released by the National Drought Mitigation Center, and farmers are feeling the need for moisture.

“We could use some rain,” Iowa State Extension field agronomist Rebecca Vittetoe said. “The lower temperatures can help. We also have some lower humidity which makes it more comfortable for livestock and us to be out there, but there is also a higher evapotranspiration demand.”

In less humid environments, evapotranspiration demand can be higher, meaning more moisture could be absorbed into the air.

Vittetoe, who focuses her attention on east-central Iowa, also said she hopes for temperatures right around average, as extra heat will quicken the grain-fill process, but lower temperatures may not provide as much benefit.

The drought monitor is also showing parts of central Iowa, such as Dallas County, affected by some abnormally dry conditions. Mike Witt, an ISU Extension agronomist who covers the counties just west of Dallas County, said the crop has withstood some of those conditions, receiving just enough moisture to stay productive.

“The later planted corn is probably not tasseling yet, but it’s pretty close, whereas there are some things that are past R1 or past the silking stage,” Witt said. “We are a little scattered, but that’s pretty standard across the state right now.”

Weather will be a crucial aspect for crop development and eventual yield.

Current weather patterns strongly suggest an early freeze this year, Al Dutcher, Extension climatologist with the University of Nebraska, said. This will follow an August he expects to be cooler than normal.

Dutcher says with much of the crop behind schedule, cooler weather in August will slow development and reduce the growing degree days necessary to push the crop more quickly toward maturity.

“It takes three consecutive growing degree days in late September to equal one day in early August,” he says. “It will be interesting to see if we start September with cooler or warmer temperatures.”

Dutcher says the forecast should increase current volatility in the grain markets.

October’s forecast indicates the western Corn Belt could see some moisture issues, Dutcher says.

“This all depends on many factors and is always subject to change,” he says. “The next few weeks should be very interesting when it comes to weather.”

With weather out of a producer’s control, Witt said the major issue bothering farmers in his area is the emergence of thistle caterpillars.

“That would be the big insect thing that’s going on out there,” Witt said. “Some fields didn’t have a lot of damage, and some had significant damage. I believe the second generation is winding down now, and more butterflies are occurring right now.”

Vittetoe said thistle caterpillars have been present in east-central Iowa, even if it is not as prevalent as their western Iowa neighbors. She said the second generation is wrapping up, but urged farmers to keep their eyes open for a third.

In east-central Iowa, the major issues have centered around weed management.

“You had a good plan and then the weather didn’t cooperate for when you wanted to put your pre or post on,” Vittetoe said. “That’s been a challenge this year.”

Vittetoe said at the end of July through early August, they are fielding more calls about crop injury from dicamba.

“I’m not surprised because a lot of the post-(emergence) herbicide applications didn’t get made until after the 4th of July, so it usually takes 10-14 days to see those initial injuries,” she said.

Additional reporting from Jeff DeYoung, Iowa Farmer Today.