Protecting against the $1B beetle

JOHNSTON, Iowa — Often called the $1 billion beetle, corn rootworm pressure is costly from both control costs and yield loss.

“One of the big pests we’ve fought for years and every farmer has, especially in the past if it was corn-on-corn, but now in the rotated acres, is corn rootworms and corn rootworm larvae feeding on our crops,” said Matt Essick, Pioneer commercial unit agronomy innovation leader in the western United States.

“We have multiple things that we can deploy to help protect against this pest, but one of the first things that we like to do is monitor it to see how many rootworms are out there in the fields to make sure we employ the right management tactics.”

An emergence cage can be used to trap emerging adults in fields during the growing season to monitor corn rootworm pressure.

Essick noted Pioneer’s ongoing trials in northwest Iowa that monitor corn rootworm pressure in Qrome and Vorceed Enlist corn, as well as non-treated corn.

Vorceed Enlist corn combines next-generation corn rootworm protection with the Enlist weed control system to give flexibility to manage insects and diseases.

Vorceed technology features three ways to protect against corn rootworm, including an RNAi plus Cry3Bb1 approach in combination with the Bt proteins in DP4114.

Pioneer brand Qrome seed corn products include a molecular stack of the Bt proteins from the Herculex I and Herculex RW traits for above- and below-ground insect protection.

“These emergence cages have allowed us to capture a tremendous amount of data on the efficacy of our management practices. So, whether it’s an insecticide treatment, whether it’s a seed treatment or if it’s just no practice at all, what differences are we seeing in corn rootworm emergence?” Essick said.

“We do an extremely good job, whether it’s Qrome or Vorceed, in reducing adult emergence from a field, and that’s something that’s extremely important.

“Vorceed adds one more trait. The RNAi technology allows us to really reduce that the number of corn rootworms even further than we’re already doing. To me, this is something that’s extremely exciting.

“Qrome and Vorceed are our primary go-to-market tactics for managing those pests. They both do an extremely good job of keeping our roots protected across the different environments that we experience.

“We’re able to do a pretty good job of controlling it. We just have to be careful to avoid too many years of continuous corn and managing with the same practices. If we have high pressure situations, we don’t just want to rely upon one management practice. We probably want to look at managing adult beetles and maybe even a soil-applied insecticide to go along with some of the traits.

“It all depends on what pressure levels are in those fields. Don’t rely on just one thing, but as a whole, we have the ability to minimize rootworm at one pressure better than we ever had. We’ve just got to keep an eye on certain situations.”

Tar Spot

Tar spot was first detected in Illinois and Indiana corn in 2015.

Tar spot has been found in 14 Illinois counties and 20 in Indiana, most of which were reported in single fields, according to documented cases reported to the Crop Protection Network through July 14.

Details of which counties can be found on the Crop Protection Network website at: https://cropprotectionnetwork.org/maps/tar-spot-of-corn.

Management practices include using hybrids with genetic resistance to tar spot, along with fungicides and residue management.

“It seems like since every time we focus on something, we start to notice it more. So, we’re probably looking for tar spot harder than we ever have in the past. We hear these situations where it pops up here, here and here. I would imagine that it’s probably in more fields than we realize, but it’s not to the point yet of causing yield loss this year at this time,” Essick said.

“For field conditions, we have to continue to have leaf wetness and we have to continue kind of a moderate temperature cycle. If we continue in those situations, that’s going to lead to the further development of the disease. So, probably don’t hit the panic button by any means, but definitely be monitoring the fields.

“Once we get most of the way through the reproductive cycle of corn and grain-fill, we can probably back off some of that monitoring, but it feels like right now we’re in an environment that’s a little bit conducive to foliar diseases, whether it’s tar spot or gray leaf spot, but that doesn’t necessarily mean this conditions are going to stay at.”