ROCKFORD, Ill. — John Fietsam drove from sunny southern Illinois to the snow-mounded cornfields of northern Illinois to talk about corn, corn diseases and corn pests.

So his audience at the Channel Achievement Series winter meeting may have puzzled over the question he asked after showing a photo of two corn rootworms.

“Do we have any deer hunters in the room?” he asked and several of the Channel seeds salesmen and farmers raised their hands.

“Can you tell which one is the female?” he asked the audience of his photo.

“If you’re trying to manage a deer herd, do you manage it by hunting the bucks or the does? You have to manage the does, that’s where your population is going to be driven, and it’s the same concept when you look at corn rootworm management,” he said.

Fietsam said being able to identify the females in a corn rootworm population is important when deciding what applications to use to control the corn pests.

“If you are going to do a foliar application in soybeans or corn to control western corn rootworm beetles, you better be going after the female. They tend to emerge about two weeks after the males, and there’s about a 14-day period after they emerge that they are carrying eggs,” he said.

While a whitetail doe may produce one or two offspring, the consequences for farmers of allowing western corn rootworm beetles to reproduce is far more serious.

“Each western corn rootworm female can carry 500 to 1,000 eggs, so you can see why it’s important if we’re instituting management practices, we’re going after killing 1,000 in one pop versus one in one pop,” Fietsam said.

New Remedies

He emphasized the importance of using today’s technologies, such as Genuity SmartStax, with its double mode of action for above- and below-ground protection against corn rootworms because those technologies are the basis for new technologies.

“The next-generation corn rootworm technology really builds on SmartStax with the dual-mode protection above and below ground. It utilizes a non-Bt source of rootworm control, as well. It’s a novel approach known as RNAi or RNA interference. Essentially what happens is RNA is the messenger in the cell. DNA is the identifier of that plant. RNA is what DNA encodes to tell the plant how to build proteins and how to function,” he said.

That same process happens in insects.

“If you think about this as RNA within the insect, interfering RNA, which is natural for controlling genes within cells, what it does is essentially cause the breakdown of that messaging RNA that’s encoding for proteins. If you interfere and block that message, the cells within that insect can’t remember how to produce those key critical proteins and over time, the insect dies. It’s a very specific approach that’s unique to corn rootworm,” Fietsam said.

He said it is not transferable to other insects, including beneficial insects.

“The RNAi is matched specifically to the RNA of the rootworm, so it’s not something that has impact on other insects, and it’s highly, highly effective for controlling corn rootworm,” he said.

But in order for the new technologies to work, Fietsam said farmers need to continue to both scout their own fields to see what insect pressures they have and where and when and then implement all the tools available in today’s toolbox to control those pests.

“The key is being in the field and actually seeing what’s out there,” he said.

Rotation Works

Crop rotation remains an effective deterrent against various pests.

“We have tools that are effective against all of these key pests, whether we look at crop rotation, which is still a very key and important management practice as we look at corn rootworm in particular,” Fietsam said.

Even with variants in the populations of western corn rootworm and northern corn rootworm, rotation remains a primary way to disrupt the cycle. That can be the case especially if corn rootworm numbers have skyrocketed in areas.

“When we do get into that really heavy corn rootworm scenario, I just want to reinforce what we consider best management practices — just reiterate the importance of rotation. It is a very effective tool in resetting that population,” Fietsam said.

Hitting the reset button with a rotation also provides other benefits.

“It’s also good if you look at a four-year span, especially with today’s commodity prices, in optimizing yield and profit potential on that acre over a period of time. One year in soybeans tends to get you away from that yield penalty that’s so often associated with continuous corn production,” Fietsam said.

Other tools in the current toolbox include traits seed treatments and insecticides.

“We have the suite of Genuity insect protection traits that allow you to choose the level of protection you want, whether that’s dual mode of protection above and below with Genuity SmartStax, where you do have that moderate to high corn rootworm pressure, or, if you get into the part of the state with lower pressure, utilizing a Triple or even a Double-PRO that doesn’t offer rootworm protection. The seed treatments provide a nice layer of protection against pests like wireworm, black cutworm, white grubs or the Japanese beetle grubs,” Fietsam said.

Seed treatments allow farmers to control multiple insects, including corn rootworms.

“Also with the option of Poncho VOTiVO allows us to go after nematodes, as well, especially in that corn-on-corn scenario where we’re starting to see some of those nematode populations become more important,” Fietsam said.

Insecticides provide an additional layer of protection.

“We’re always got the insecticides, whether that’s soil-applied insecticides going after corn rootworm or some of our key secondary pests or the well-timed foliar applications going after some of those key foliar pests or managing corn rootworm for the subsequent corn crop, all key tools in the tool box,” Fietsam said.

He said farmers need to focus on entire populations of insects.

“It’s a numbers game when you look at some of these populations that are through the roof. If you’re killing 90 percent, you’ve got a couple hundred rootworms that emerge, lay eggs and all at once, your population is back to exponential levels in no time flat,” he said.

A whole-field approach needs to be used.

“We need to be implementing the tools we have available to manage not only the protection of the roots, but the populations in general,” Fietsam said.