Genetically modified corn may be vulnerable to pests


December 21st, 2011

Lincoln, NE – Farmers know all too well that rootworm and corn don’t go together. That’s why it was big news last month when an EPA report found that genetically modified corn might not be able to battle the unwanted pest effectively.

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During the winter, agronomist Ben Pinkelman spends a lot of time inside, sitting at a computer. But in the summer, his office is on wheels his pickup truck.

A cropduster sprays insecticide over a Nebraska corn field to control rootworm, a devastating pest. (Photo courtesy Wikimedia)

Pinkelman is a crop consultant and oversees more than 30,000 acres. Of those acres 3,000 show signs of rootworm infestation.

“I’ve seen it on my south end, east end, west end, north end so I’ve seen it kind of my whole territory here in northeast Nebraska.”

The signs of an infested field? The plants aren’t standing well in the rows, they’re tilted or there’s just areas where the corn is lying flat on the ground; All this because the pests are eating at the roots.

What’s common about these fields is they’re planted continuously with corn.

“If we throw the same thing at it year after year after year after year it’s going to beat us,” Pinkelman said. “So we have to think longer term and integrate more approaches to keep the rootworm guessing.”

The EPA has issued a report last month that sees the very same problem in fields it surveyed in Iowa, Illinois, Minnesota and Nebraska. The report stated that a trait in one of Monsanto’s genetically engineered corn seed which has been on the market since 2003 may be losing some of its effectiveness against rootworm.

The rootworm eats at the root of crops, causing widespread damage when a cornfield is infested. (Photo courtesy Wikimedia)

“We take the EPA’s report very seriously and we do know that farmers have faced hot spots with high populations of rootworms for years,” said MiMi Ricketts, a spokesperson at Monsanto. “Even prior to the introduction of insect protected trait technologies. Today there are geographical pockets of heavy rootworm infestation in areas where there’s been a long history of corn-on-corn plantings.”

In Nebraska that’s becoming a common planting pattern, especially for cattle producers.

“There’s an economic incentive to grow your own corn rather than buy it for somebody else, especially with the higher value of corn these days,” said Bob Wright is a professor of entomology at the University of Nebraska-Lincoln. “That’s sort of exaggerating or exacerbating the issue in terms of why people are growing continuous corn.”

Farmers facing a rootworm infestation do have options. They can rotate their fields to a different crop like soy beans a plant where the rootworm cannot survive, essentially breaking the life cycle of the pest. They can switch to a different seed that has multiple traits that kill the rootworm, or they can switch to older methods of pest control like soil insecticides.

“If management practices that led to problems in a few fields are continued on a larger scale, the problem likely will become bigger,” said Aaron Gassman, an Assistant Professor of Entomology at Iowa State University whose research was cited by the EPA in its report. Gassman examined rootworm damage in Iowa fields in 2009.

“It’s hard to know just how big of an issue this could become; it could become a substantial problem down the road if things don’t change now,” Gassman said.

Ben Pinkelman, the agronomist in northeast Nebraska, notes that rootworm resistance is an ongoing battle for farmers no matter what seed they plant. But he does see a broader concern in this case.

“We’ve got a trait and these traits are supposed to be infallible is the general belief out there. It’s never happened before,” Pinkelman said.

Insecticides have failed before, cultural controls have failed before, this is kind of a first.”

The stakes are high; according to the Corn and Soybean Digest roughly two-thirds of the US corn crop has been genetically modified to ward off pests.

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