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A harvest crew with Tuxedo Corn Company works to inspect each individual sweet corn plant before harvesting in a field west of Olathe off Falcon Road Wednesday morning July 19, 2023. (William Woody, Special to The Colorado Sun)

A little worm is causing big problems in the sweet corn fields of the Uncompahgre Valley.

Corn earworms, known to entomologists as Helicoverpa zea, have infested 30% to 40% of the sweet corn in the farming area between Montrose and Delta that produces Colorado’s most craveable tender and sweet corn each summer.

The earworms have been hatching in the fields of about two dozen growers — fields that have annually produced about $15 million of agricultural revenue since sweet corn became the valley’s most well-known crop.

Corn earworms have always posed a creeping danger, but there has not been a year before when they turned up en masse, munching the tips of otherwise perfect ears of corn, at the start of the season.

“We are scrambling. We are off balance. We are sad. We are embarrassed. We did not see this coming,” said David Harold, the son of John Harold, who founded the Tuxedo Corn Company, the state’s largest sweet corn producer, 41 years ago.

Tuxedo corn under the brand name Olathe Sweet goes to grocery stores across the state and nation via Kroger, City Market and King Soopers stores.

Tuxedo workers discovered the worms in the corn in mid-July just as harvest was gearing up to begin — and just as King Soopers was set to kick off a large-scale advertising campaign for the popular corn. The ads were pulled and Tuxedo went into damage-control mode in the fields.

John Harold wrote to Sen. Michael Bennet last week urging him to let U.S. Secretary of Agriculture Tom Vilsack know about the corn earworm problem and hopefully have him direct agronomists with expertise in sweet corn production to help out.

“We need another set of eyes to tell us how these worms were so successful this year,” John Harold said.

In his brief letter to Bennet, he didn’t mince words about the dire situation he and other corn farmers are facing: “We have an EMERGENCY in sweet corn production in Western Colorado.”

Tuxedo Corn Company founder and farmer John Harold, center, holds a meeting with staff while crates of Olathe Sweet corn are iced at the company’s headquarters and shipping facility. (William Woody, Special to The Colorado Sun)

The Harolds said they are having to leave about 400 acres of fields entirely unpicked because the worm is so pervasive. In other fields, workers are having to laboriously tug on the silk or pull back the tips of the husks to check for worms before an ear of corn can go into boxes bound for grocers. In some fields, the workers make a first pass, finding and tossing wormy ears and a second pass to pick marketable corn.

It comes down to about 9,200 ears being pitched per acre. Normally, an acre produces about 23,000 ears suitable for markets. Tuxedo is only packing about 3,000 boxes of corn per day for shipment to stores compared with about three times that amount in a normal year. That corn may be a bit more expensive this year because of the infestation, the Harolds said.

Cracking the corn worm code

There are a multitude of possible reasons why the moths that lay the eggs that produce the worms were able to successfully invade the crop this year, said Melissa Schreiner, an entomologist with the Colorado State University Tri-River Extension office in Montrose.

“It is just a perfect storm of a mess. There are so many factors we are looking at. It’s been quite challenging,” Schreiner said. “We have lots of folks really trying to knock their heads together to try to crack the corn worm codes.”

To start with, 2023 has been what Schreiner calls  odd in terms of weather.

After years of drought, this year’s corn crop had plenty of early moisture. The late spring and early summer temperatures were cooler than normal. There were no April freezes to kill off the corn earworm moths. And there were strong prevailing southeast winds that could have helped to bring the moths into the area from southern farm fields. Add to that, the broiling triple-digit heat of the past few weeks.

A harvest crew with Tuxedo Corn Company works to gather ears to be feed onto a large harvesting machine. (William Woody, Special to The Colorado Sun)

Helicoverpa zea moths produce two other pests besides the corn earworm. They are all the same species. They just go by different names. They are called cotton boll worms when they infest cotton. In tomato crops, they are known as the tomato fruit worm.

If the worms are going to be a problem in corn, they don’t usually turn up until late in the growing season. Growers spray the crops early in the corn’s development to kill off the moths before they can turn into worms.

This year, the usual insecticide didn’t work well, and the reason why is at the heart of CSU’s and the Harolds’ investigation into what happened to allow the worms to take hold like they have.

David Harold said he is second-guessing Tuxedo’s pest management program. The fields were sprayed as usual, but the corn was planted later than normal because of the weather. Late-planted corn means that the silk on the ears of corn forms at a time when more moths are out and about searching for silk to lay their eggs in.

Crews work a field off Falcon Road west of Olathe, picking ears of sweet corn for market. The owners of Tuxedo Corn Co. expect to leave 400 acres unpicked because of earworm infestation. (William Woody, Special to The Colorado Sun)

Schreiner said she does not believe poor crop management on the part of the Harolds or other growers caused the worm infestation. She and her colleagues are conducting a study to determine if the corn earworms have developed resistance to the pesticides that normally kill them.

“It’s possible moths coming in have already been sprayed elsewhere.  We are wondering if they come in resistant or if the resistance develops over time in the corn,” she said.

Schreiner had already been planning a study of corn earworms before the current emergency arose. She said they are using a Specialty Crop Block Grant from the Colorado Department of Agriculture to do field trials on the worms that may yield some answers as soon as next week.

Shortage of visas for workers is compounding the problem

 The Harolds say more of the corn crop could possibly be saved and salvaged for other uses if it weren’t for political and legislative problems.

David Harold blames the strict rules imposed by Senate Bill 87, the 2021 law that gives farm workers a raft of protections, including that they be paid overtimes, and the demands of H2-A visas that allow foreign workers to be in the country on temporary visas. He said all the restrictions do not give growers the wiggle room to deal with unforeseen crises like the corn earworm infestation.

A harvester inspects each ear of sweet corn before picking. (William Woody, Special to The Colorado Sun)

He said if Tuxedo workers could spend longer hours in the fields — something they are willing to do — they would be able to more thoroughly inspect and pick more corn. More visa workers are expected to arrive this weekend, giving the growers some relief.

David Harold said they are carefully examining the corn because “we take pride in delivering an ear of corn with no defects.”

John Harold said there may also be some relief in later corn crops being less infested. The Harolds plant corn in stages to maintain a supply into late summer.

A sad note in the infestation is that the corn with the worm defects is perfectly edible. The little brown-headed worms are most often found feeding on the tips of otherwise healthy ears of corn. Cut off the top and the remainder of the ear is as good to eat as any coveted ear of Olathe Sweet.

But, at this time, the Harolds don’t have the workers or the infrastructure it would require to process defective corn, and buyers aren’t willing to do it because there is enough healthy corn from other areas this year that they don’t need to be dealing with wormy ears.

Consumers are also a factor. Most don’t like to shuck an ear of corn and be greeted by a worm. That pickiness, Schreiner said, makes it easier for something like a tiny worm to become an outsize problem.Sweet corn fans will still have the chance to revel in their favorite summer produce next weekend in downtown Olathe. The Olathe Sweet Corn Festival will go on as planned — with plenty of corn served Aug. 5.

Crates of Tuxedo Corn Company’s Olathe Sweet corn are iced following USDA inspection. (William Woody, Special to The Colorado Sun)

CORRECTION: This story was updated at 11 a.m. July 27, 2023, to correct the volume of corn Tuxedo Corn Co. is shipping daily to markets. The farm is sending about 3,000 boxes a day compared with about three times that amount daily in a typical season.

Special to The Colorado Sun Email: Twitter: @nlofholm