What is going on with Iowa corn?

Despite nearly 30 tornadoes, a derecho, and portions of the state reporting at least 350% of normal rainfall, corn planting and emergence continued across Iowa.

A field of recently emerged corn and soybeans in Grandview, Iowa
Photo:

Natalina Sents Bausch

Despite nearly 30 tornadoes, a derecho, and portions of the state reporting at least 350% of normal rainfall, corn planting and emergence continued across Iowa, said USDA in the latest Crop Progress report published May 28.

USDA’s 2024 corn crop stats

According to UDSA’s Prospective Plantings report published on March 28, Iowa farmers are expected to plant 12.8 million acres of corn in 2024.

Corn planting

Despite just 2.3 days suitable for fieldwork in the seven-day period ending May 26, Iowa corn farmers planted 10% of this year’s corn crop. USDA says 88% of the 2024 corn crop is in the ground. That’s behind both the five-year average of 92% and last year at this time when 97% of Iowa corn had been planted.

Corn emergence

The state reached an important benchmark as more than half the corn crop has emerged. USDA says 66% of Iowa corn had emerged the week ending May 26. That’s up from 47% the week prior. However, that’s behind the five-year average of 70% and last year at this time when 79% of Iowa corn had emerged.

Corn condition

The latest USDA Crop Progress report rated Iowa corn 1% very poor, 4% poor, 22% fair, 54% good, and 19% excellent. This is the first week of the season corn condition ratings were published.

Regional breakdown

Multiple rounds of thunderstorms brought torrential rainfall, damaging winds, hail, and destructive tornadoes to the state on May 20 and 21.

The statewide storm system included an EF4 tornado with peak wind speeds of 175 mph to 185 mph. Over its 44-mile path, the twister destroyed countless homes and businesses, injured 35 people, and killed five.

An aerial view shows devastation left behind after a tornado tore through town on May 22, 2024 in Greenfield, Iowa
An aerial view shows devastation left behind after a tornado tore through Greenfield, Iowa. Multiple deaths and injuries have been reported from a series of tornadoes and powerful storms that hit several Midwestern states.

Scott Olson/Getty Images

Just a few days later on May 24, a derecho brought high winds, hail, and more tornados across the state.

Summarizing recent weather Iowa State Climatologist Justin Glisan said, “Iowans experienced one of the most active reporting periods in recent memory with nearly 30 tornadoes, a late week derecho and anomalously wet conditions; many northeastern stations reported at least 350% of normal rainfall.”

“Our hearts go out to all the Iowans and communities who have been affected by the recent rounds of devastating severe weather. The outpouring of support for those affected highlights the remarkable strength of our state and its people. Iowans are resilient and we will get through this together,” said Iowa Secretary of Agriculture Mike Naig. “Planting progresses as conditions allow, but many farmers continue to face delays. Outlooks into the first week of June show elevated chances of warmer temperatures and near-normal rainfall chances, which hopefully will lead to conditions more favorable for field work.”

Northwest Iowa

Although northwest Iowa had been plagued by drought conditions as intense as D4 exceptional drought in the 2023 growing season, the latest Drought Monitor maps show the region is free of drought stress. 

Map of Iowa drought conditions

U.S. Drought Monitor

In fact, several inches of precipitation above average have been recorded so far this month. USDA rated topsoil moisture in Northwest Iowa 0% very short, 2% short, 60% adequate and 38% surplus in the latest Crop Progress report. Over the same time period, subsoil moisture rated 0% very short, 4% short, 72% adequate, and 24% surplus in this part of the state.

Map of precipitation departure in Iowa for May 2024 so far

Iowa Environmental Mesonet

“It has been difficult to get ahead of weeds with only small windows of time with low wind and dry fields,” said Iowa State Extension Field Agronomist Leah Ten Napel in a blog post published May 21. Ten Napel serves Cherokee, Ida, Lyon, Monona, O'Brien, Osceola, Plymouth, Sioux, and Woodbury counties. She noted weed control issues may arise later this year because of late or missed applications, or excessive rainfall following applications.

The agronomist also mentioned there have been reports of soil crusting causing emergence issues, but stands look good in fields where crops got out of the ground fast.

Map of ISU Extension field agronomist regions

Iowa State University Extension

In the next region east, Iowa State Extension Field Agronomist Gentry Sorenson reported, “Heavy rain occurred during the overnight hours of May 20 into May 21, with rainfalls ranging from 1 to 4 inches across my region. Hail was also reported in areas of Clay and Palo Alto counties.”

Crusting was also reported across the region, noted Sorensen, saying rotary hoe operations were performed on several fields to help break the crust and help emergence of corn.

Some northwest Iowa farmers have started replant work in areas that had standing water earlier in May. Sorenson said, unfortunately some of those areas were underwater again after more storms moved through the area.

Northcentral Iowa

Angie Rieck-Hintz is the Iowa State Extension Field Agronomist covering Worth, Cerro Gorodo, Humboldt, Wright, Franklin, Webster, Hamilton, and Harding counties.

In a May 21 blog post, Rieck-Hintz explains, some corn in her region was planted in less than ideal soil moisture conditions leaving concern for emergence and rooting. “Emergence uniformity is of concern in many fields and a few farmers have shared they hope to be able to replant not only the wet areas, but in some cases, entire fields.”

Northeast Iowa

Terry Basol serves Mitchell, Howard, Floyd, Chickasaw, Butler, Bremer, Grundy, and Black Hawk counties as an Iowa State Extension Field Agronomist. He also noted potential flooding and ponding issues in the area after the May 21 storms.

In Region 5, Iowa State Extension Field Agronomist Josh Michel noted some farmers in the area have finished up planting. He covers Winneshiek, Allamakee, Fayette, Clayton, Buchanan, Delaware, and Dubuque counties.

West central Iowa

Kelly-Garrett-planting

XtremeAg

Kelly Garrett raises corn, soybeans, and cattle in Crawford County, Iowa. Although he’s been done planting soybeans for quite some time, the operation finished planting corn on May 20. He's happy to be finished planting for the season, but the talk of May 20 being late, “in my opinion is ridiculous,” he said in a recent Successful Farming blog post.

I don’t believe there is any yield penalty for planting corn on May 20. I would be comfortable planting full season corn up until May 25,” he added, noting in 2008 he planted corn on Memorial Day. “I wish I could plant all my corn between May 5 and 20, but we can’t always control the weather.“

Central Iowa

Following the May 21 storms, Meghan Anderson, Iowa State Extension Field Agronomist, received reports of flooded fields, roads, washed out fences, and other related issues.

The corn crop across Boone, Story, Marshall, Tama, Dallas, Polk, Jasper, Madison, and Warren counties is quite variable, she noted. Replant has already happened in some central Iowa fields, Anderson reported in a blog post published May 21.

On May 21, an EF-2 tornado traveled 41 miles from Polk into Story County. The National Weather Service estimates peak winds reached 135 mph. Two storm related injuries were reported.

On the same day, two EF-O tornados were reported in Warren County. Wind speeds reached 75 mph downing trees near Martensdale and Spring Hill.

On May 24, four tornados swept through Anderson’s region in Polk, Warren, and Boone counties. Although they were all rated EF0 by the National Weather Service, peak winds were estimated to be 85 mph. The Storm Prediction Center has confirmed the overall event as a derecho with damaging wind gusts from central Nebraska through northwest Illinois.

East central Iowa

In Region 8 Iowa State Extension Field Agronomist Rebecca Vittetoe heard reports of soil crusting causing emergence issues. She urged farmers across Benton, Linn, Jones, Poweshiek, Iowa, Johnson, Marion, Mahaska, Keokuk, and Washington counties to scout for black cutworms.

Black cutworm is a migratory pest that arrives in Iowa with spring storms each year. The moths lay eggs in or near crop fields and the larvae feed on leaves or cut corn seedlings. Corn plants are at risk until V5. More information can be found in Iowa State Extension’s article, “Start scouting for black cutworm in emerged corn.”

Southeast Iowa

Further to the east and south, in Region 9, Iowa State Extension Field Agronomist Virgil Schmitt has had one report of black cutworm. A professional crop scout “found several sizes cutworms not at threshold in V2-V3 corn in Louisa county on May 21. It was a field that had a good cover of winter annuals to attract moths," said Schmitt.

On May 28, he noted two calls about True Armyworms in his territory.

Southwest Iowa

Southwest Iowa was hardest hit by the recent severe weather. USDA’s Crop Progress report noted just 1.1 days were suitable for fieldwork in southwest Iowa during the week ending May 26.

On May 21, the EF-4 storm known as the Greenfield Tornado traveled from Page to Adair Counties. EF4 damage was located within the community of Greenfield and across rural portions of southern Adair County, said the National Weather Service (NWS).

As the EF-4 tornado began to dissipate northeast of Greenfield, the storm cycled producing another tornado which extended into northeast Adair County. This EF-2 tornado traveled nearly 12 miles with peak wind speeds reaching 115, said the NWS.

The same day, a third tornado, rated an EF-3 by NWS traveled 32 miles from Page to Adams County. At its peak, the twister was 1,300 yards wide.

A fourth tornado, rated an EF-1 by NWS traveled more than 12 miles across Adams county on May 21. Peak wind speeds reached 95 mph, reported the NWS.

Later on May 21, another EF-1 tornado was reported in Audubon County. The path of the tornado stretched over seven miles and reached peak wind speeds of 95 mph, estimated the NWS.

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