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
“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,”
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,”
He said it is not transferable to other insects, including
“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.
Crop rotation remains an effective deterrent against various
“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
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
“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,”
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,”
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
“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,”