Non-GMO Weed Control
Tank Mix Products To Provide Broad Spectrum Weed Control
PRINCETON, KY
Weed control options for non-GMO cropping
systems was a topic discussed by
Dr. J.D. Green, University of Kentucky
extension weed scientist, recently. He also addressed
other general weed management principles.
“When selecting a weed control program we
need to be sure it’s effective on the weed species
that we’re trying to manage and control,” he
said. “It is important that programs are fairly
easy to use as well as they must be economically
viable within the system that we’re managing
those weed problems.”
The level of management needed for effective
weed control tends to be higher in a non-GMO
program. Growers must make sure they’re paying
attention to their specific weed problems
and that sometimes means tank mixing two or
more products together to get the same broad
spectrum of control that we have come to expect
with some of the GMO technologies.
“Typically, the most consistent weed control
that we see is using a soil- applied followed
by a post-emergence herbicide program,”
Green said. “Effective weed control programs
also result in optimum yields based on research
through the years. The most consistent high yielding
crops are obtained when we use a soil
residual followed by a post emergence program.”
On the other side of the spectrum farmers
must think about choosing between planting
GMO seed because of weed resistance. Any time
one relies on one herbicide technology, there is
a higher potential for weed resistance to occur.
“We saw that back in the 1980s and early
1990s when ALS chemistries were the predominant
herbicide programs for soybeans,” he explained.
“In less than five years a farmer using
products like Pursuit, Scepter, Canopy, and
Classic had to deal with weed resistance. Now
we’re talking about and are concerned about resistant
weeds from over use of glyphosate, with
the Roundup Ready technology program.”
Timing of herbicide applications is one of the
most important factors in either GMO or non-
GMO crops. If we wait five weeks or so before
we make that first herbicide application we
could be loosing five to 10 percent of our yield,”
he said. “In fact, I’m not so sure a lot of producers
aren’t loosing yield because they want to
make sure all the weeds are up and emerged before
they make that first application. So it’s a
trade off between spraying weeds at an optimum
size of three to six inches, let’s say in soybeans,
versus trying to control them all later on.
“If we use an at planting soil-residual type herbicide
we can typically minimize the problem
and get good control early; then we shift the
need for the post application later into the season.”
One of the primary benefits of soil residual
herbicides is that growers can obtain more consistent
season-long weed control, and also have
more flexibility in making post applications in
seasons like this past year when we received excessive
rainfall. There have been fewer days and
less opportunities to be timely in making postemergence
herbicide applications this season.
“Using a soil residual herbicide allows one to
use different herbicide modes of action and minimize
the potential for weed resistance to occur,”
Green said. “I’m not so sure that in some crop
fields where good weed control has been
achieved for the last few years that a good soil
residual herbicide program may be all that is
needed. The weed seed bank has been reduced
to where weeds can be effectively managed with
a soil residual herbicide treatment.”
There are a variety of different soil applied herbicides
that can be used in soybeans. Whether
it is something that targets broadleaf weeds or
mostly grasses, several options are available. A
group of other products are available for an
over-the-top treatment later, if needed.
“As I mentioned earlier, we may need to tank
mix some products together depending on what
the specific weed problems are, but you certainly
need to know your fields if you’re going to
use that as your total focus for weed control,”
Green said.
He noted the overall cost of weed management
has changed.
“In the past, we primarily thought about only
the cost of herbicides when we talked about
overall weed control costs,” he explained. “In
today’s world with the technology cost associated
with the seed traits that are available to us,
certainly we pay a premium for those seed
traits; it’s not just for the weed management
part of it but there’s an additional cost when we
use a GMO technology that we need to account
for in calculating total cost of weed management.
If you look at the cost of the technology
with the seed trait included it can be somewhat
comparable to the total cost of a non-GMO program.
The bigger difference or what can be a difference
is the overall level of management I
talked about earlier.”
In summary, Green said an effective weed control
program is one that provides broad spectrum
weed control; he also urged farmers to
avoid reliance on one weed control program to
minimize weed resistance.
“We should try to make herbicide applications
as timely as we can since we want to ensure
that we have an economically feasible, and viable
weed control program,” he summed. Δ
BETTY VALLE GEGG-NAEGER: Senior Staff
Writer, MidAmerica Farmer Grower
Weed control options for non-GMO
cropping systems discussed
by Dr. J.D. Green, University of Kentucky
Extension Weed Scientist.
Photo by John LaRose, Jr.