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A little worm destroyed last year’s sweet corn crop. Here’s how Colorado farmers are fighting back.

Tuxedo Corn and other growers around Olathe have been working on a trio of responses to try to thwart — or at least slow down — the corn earworm.

Nancy Lofholm 4:14 AM MST on Feb 13, 2024

from The Colorado Sun

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)

Olathe farmer John Harold had been producing Olathe Sweet Corn for nearly half a century when last summer he finally got frustrated enough to use the Q word.

He contemplated quitting.

The 83-year-old Harold had overcome years of weather and workforce-related challenges, but this time a tiny worm had destroyed nearly half of the family’s 2023 crop and cost his Tuxedo Corn Company a bundle — more than he wants to reveal.

“I was ready to throw in the sponge,” Harold said as he chatted with a reporter on his cell phone while driving around his Olathe-area farm doing what he loves too much to quit. 

Instead of giving up on corn, Harold and his son, David Harold, have spent the fall and winter huddled with other Uncompahgre Valley corn farmers searching for ways to have another go at the $15 million crop they put on the map under the brand name Olathe Sweet. 

They are preparing to put corn seed in the ground in mid-April, weather permitting, after figuring out the best ways to thwart the Helicoverpa zea — the corn earworms that infested last year’s crop. 

This year they plan to be on the lookout for the pests early on so they won’t be reacting to a worm-fueled disaster like last year.

David Harold is less optimistic than his dad. Even with dedicated worm surveillance, he doubts they will be able to beat the earworm in 2024.

“I have no confidence,” he said. “There is nothing on the horizon that makes me feel like, ‘oh, yeah everything is going to be like before.’ There is no solution to the worm problem.”

“I am planning on planting corn because I am just stupid — that and we can’t give up now. We don’t want to lose our markets,” he said.

Three ways to slow the spread of worms

The Harolds have been working on a trio of responses to try to thwart — or at least slow down — the corn earworm. 

They have the help of Colorado State University researchers to identify chemical combos that might overcome the worms’ possible resistance to older insecticides. They are going to be experimenting with drones to apply some of those insecticides. And if those measures fail, they have potential new buyers that are willing to purchase worm-damaged corn. 

They are also leaning on what carries farmers through so many years — luck.

“It’s a crapshoot for sure,” John Harold said. “In this racket there are no guarantees.”

Last season, the crapshoot did not land in favor of the Harolds and the two dozen or so other Olathe-area sweet corn farmers.

Early moisture in the Uncompahgre Valley was followed by cooler than normal early summer temperatures. Just as the corn was tasseling, strong winds from the southeast carried hordes of the moths that lay earworm eggs to the Olathe area. There were no April freezes that might have killed off the moths, so they nestled into the corn plants and went to work reproducing by depositing eggs in the cornsilk on tens of thousands of ears of corn. 

“We battle pressure from this pest regularly, but last year there were perfect conditions for it to move in here,” said Melissa Schreiner with the Colorado State University Tri-River Extension office in Grand Junction. 

Worms were discovered gnawing on the tips of corn ears in mid-July just as the Harolds were gearing up for harvest, and their biggest buyer, Kroger, was preparing to kick off a large-scale advertising campaign.

The advertisements were pulled and everyone from the field workers to congressional representatives jumped in to try to help deal with an agricultural emergency brought on by a worm.

The worms, well established by then, caused a panic. Once corn is badly infested with helicoverpa zea there is little to be done.

The Harolds had no option but to leave about 400 acres of corn unpicked. In some fields, pickers had to peel back the tips of corn ears to look for worms, slowing down the normally speedy picking process. Of the usual 23,000 ears produced per acre, as many as 7,000 had to be pitched in the fields.

The Harolds had the complication of having to deal with the new regulations imposed by Senate Bill 87 that passed in 2021. One of the bill’s measures requires growers to pay time-and-a-half overtime. David Harold said with longer hours, the pickers could have salvaged more corn, but with the huge losses in the crop, the Harolds couldn’t afford to take on that burden.

By the end of the season, the Harolds had produced about 330,000 cases of corn, far short of the normal production of 500,000 cases.

Scouting for signs of infestation

This year, rather than planting corn on 1,500 acres like last year, Tuxedo will plant somewhere between 900 to 1,200 acres of sweet corn. 

They will be focusing early in the season on what Schreiner calls “scouting” – looking for eggs on the corn silk to determine if insecticides need to be applied at higher rates than normal or if the timing of when they are applied will make them more effective.

There is one theory — still unproven — that the corn earworms have developed a resistance to the old pesticides that used to keep them in check. CSU has been studying combinations of insecticides that might be more effective against the worms. But, just as with antibiotics for humans, growers are running out of effective chemicals against the pests.

Products that show some promise for better efficacy against the worms have not yet been approved by the Environmental Protection Agency. David Harold said it would likely take several years to get approval for new earworm insecticides. 

In the meantime, CSU will be continuing field testing of insecticides this season. Schreiner said her office is waiting on a U.S. Department of Agriculture grant that would fund more CSU studies in the Olathe area fields that would go beyond insecticide applications. As part of those studies, CSU researchers will look at GMO corn as a worm-resistant alternative to the traditional heritage varieties of corn. Those studies will include taste tests with consumers.

“This problem has started important conversations, and we can bring more support to this part of Colorado,” said Schreiner who has been impressed by how growers have come together to battle the worms.

In another innovative move, the Harolds will be experimenting with applying insecticides to some of their fields using drones rather than traditional crop-dusting planes. Drones can fly as low as 2 feet over the corn plants, and it is believed that the force of their rotors help push the chemicals down into the corn for a more direct application.

John Harold said drone applications appeared to help some of the corn fields last year. David Harold said he doesn’t believe they were any more effective.

“We are not always on the same page,” David Harold said. 

If the worms reappear in droves this year, the Harolds’ backup plan is to literally cut off the worms that tend to stay at the tips of the ears. John Harold said they have contacted a Cincinnati-area food company that sells shucked corn with the tips removed. It is sold in plastic-wrapped trays that make for easy microwave preparation.

Even if that happens, John Harold said there will still be bulk corn — whole ears in the husks — for local sales.

John Harold said he hopes that fears of no Olathe sweet corn next summer will be put to rest. He said he has been approached recently by Olathe-area locals asking, “you going to plant?” They had heard rumors that Olathe Sweet seed that had put the little town of Olathe on the map would not go in the ground this spring.

One person who asked that question offered to set up a Go Fund Me Page for Olathe Sweet because he couldn’t tolerate the idea that he wouldn’t have his favorite sweet corn. 

That made John Harold chuckle.

“We are planting,” he said. “There will be corn.”

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