Unspoken Truth About Pests: Emerging Pest Pressure That Could Come to a Field Near You

In the heat of July, scouting for pests is part of the job for northern Indiana agronomist Marc Eads. While weather plays a role in pest pressure each year, this year, it isn't insects giving farmers fits, it's slugs. 

“The feeding can often be mistaken for flee beetle feeding in corn,” says Ead as he’s walking fields. “Slugs are actually not an insect, they're a gastropod. So, they are a shell-less snail,” he adds. “They do most of their damage in the early part of the growing season.”

No-till or minimum-till fields with plenty of cover, combined with cool spring weather, set up parts of northern Indiana for major slug damage.

“I have seen a field not too far from where we're standing right now that was replanted four times,” he adds.

While the Eastern Corn Belt dealt with slugs in reduced tillage fields this year, the Western Corn Belt has fields that haven’t seen a piece of tillage equipment in over 30 years. Frahm Farmland in Colby, Kan., has been no-till for decades. And the reduction in tillage practices has helped with insect control.

“I think it makes [insect control] easier,” says Christian Wilson of Frahm Farmland.

Pests Popping Up

From no-till to conventional tillage, farmers across Illinois are seeing one specific pest pop up more.

“One of those insects that we're seeing more of, and I don't really know the reason why, is wireworm,” says Farm Journal agronomist Ken Ferrie, who also owns Crop-Tech Consulting. “We're dealing with more wireworm every year.”

Ferrie says the issue is also a problem in fields farmers were forced to replant.

“The population seemed to be building, or we find more fields with wireworm issues,” says Ferrie.

While the reason remains a mystery, up and coming pest pressure is something Ferrie continues to watch.

“The other insect that we do see more of each year in Illinois is the northern rootworm beetle,” Ferrie adds. “It used to be more of an Iowa, Wisconsin bug, and it seems to be moving in, especially in the northern parts of the state. And we'll add to be dealing with that as those pressures build.”

Location, Location, Location 

As certain pest pressures build, Farm Journal Associate Agronomist Missy Bauer says it’s often geography based.

“I think it depends really where you're at,” says Bauer, owner of B&M Crop Consulting. “Like here in Michigan, we're dealing with western bean cutworm way more than we used to. 10 years ago, we didn't hardly have to deal with it at all; now it's something every year we're paying attention to.”

There’s another emerging issue happening in soils that tend to be sandier.

“Asiatic garden beetle is another new emerging pest for us here in Michigan,” Bauer says. “It likes sandier soils, and it can really cause problems in young corn and emerging corn fields and give you a lot of unevenness out there in the field.”

Factors Fueling Pest Populations

From soil type to seed type, there are other factors fueling insect populations and problems. 

“We do have corn borer building in the areas where farmers have moved to the non-Bt market for market premiums,” says Ferrie. “And if we do that for a series of years, we start to see more and more pressure build in those areas.”

As seed companies invest in more traits and modes of action, it’s helping combat some of the emerging issues. However, an entomologist with Ohio State University says growers need to stay diligent in scouting, as pest problems are also popping up in Bt fields.

“Many of the corn earworm in the South have become resistant to the types of Bt that are used to manage them,” says Kelley Tilmon, with Ohio State University. “So, not only are we getting influxes of corn earworm, we're getting influxes of Bt-resistant earworm.

As pests adapt, a constant focus in research and development may always be needed.

“That's a very important point in general for people to keep in mind, nature always finds a way around our management strategies,” she says.

But as traits continue to evolve to help farmers combat pests, Bauer says there are insects that farmers no longer battle every year due to genetics and traits to help combat certain pests.

“One pest we used to deal with, especially when I first started my career, was European corn borer,” says Bauer. “I wouldn't say we have eliminated it, as some people have conventional corn, and if you have conventional corn you still need to be out there scouting it. But where there's so much corn with traits now, that seems to be one thing we just don't have to deal with very often.”

From genetics and traits to a change in production methods on farms across the country, pest problems can create financial woes.

“If the pressure is high enough where they're actually causing economic damage, you're going to be able to find them,” says Eads.  

Even as agronomists like Eads continue to battle both known and unknown pests each year.

Read more about "Unspoken Truths About Pests" here.