Get a better handle on early weed control
Apr 16, 2021
It’s a bit of a
no-brainer that when weeds are controlled, crops perform better. But there are
deeper subtleties when it comes to how and when it’s best to control weeds to
maximize crop outcomes. How early is too early? How late is too late? What
should be in the spray tank?
Adam Pfeffer, Agronomic Systems Manager
with Bayer in St. Thomas, Ontario, says the crop itself matters when it comes
to answering some of those questions.
“Corn is unique in that it
determines a large portion of its yield potential early in development, around
the V6 stage,” says Pfeffer. “In canola, soybeans and wheat, a greater portion
of the yield potential is determined later in the growing season – often after
that early weed management period.”
And while it’s true that canola and
soybeans are more resilient than corn in the face of weed competition, yield
loss can still be significant when weeds aren’t controlled early.
Indeed, an Agriculture and Agri-Food
Canada research project looking at weed control timing in canola found that
just one weed emerging before the crop had the same negative impact on yield as
100 weeds emerging three weeks after the crop.
1 And research in Ontario
shows that soybean yields can be reduced by as much as 80 percent when weeds
are not adequately controlled during the critical weed free period.
2
New
traits improve early weed control options
Pfeffer says that the majority of growers
already include early weed management in their field plans, but it can be easy
to be lulled into complacency.
New traits like those found in Roundup
Ready® 2 Technology corn, Roundup Ready 2 Xtend® soybeans,
and TruFlex™ canola with Roundup Ready® Technology help
by providing growers with more herbicide and timing options.
Effective weed control in corn. Bayer’s
latest corn traits include Roundup Ready
2 Technology which allows
growers to control weeds early with a Roundup branded herbicide from emergence
to three-leaf. This provides excellent crop safety and sets up the corn crop to
reach its maximum potential.
More flexibility in canola. TruFlex canola gives growers more
options and flexibility when it comes to post-emergent weed control. The trait
found in TruFlex canola hybrids increases the plant’s tolerance to glyphosate,
and this increased tolerance allows for a much wider application window and control
of a wider weed spectrum.
Pfeffer says this allows growers to
spray for weeds from cotyledon right up to first flower
3, giving
them more time, if they need it, to get weeds under control.
And more weeds, too. The TruFlex
canola system has 51 weeds on the label, including some of the tougher ones
like cleavers, wild buckwheat and dandelion.
Residual weed control
in soybeans. The Roundup Ready
® Xtend Crop System combines the high yield
potential of Roundup Ready 2 Xtend soybeans with the option of two enhanced
chemistries to control difficult and resistant broadleaf weeds.
Roundup Ready 2 Xtend soybeans
carry a trait that makes them tolerant to both glyphosate and dicamba. The two
enhanced chemistry options that can be used with the system are Roundup Xtend
® with VaporGrip
® Technology – a glyphosate-dicamba premix, and
XtendiMax
® with VaporGrip Technology – a dicamba-only product that
can be tank mixed with a Roundup-branded product.
“Our research shows a good
two to three weeks of early-season residual weed control provided by dicamba in
this system,” says Pfeffer, adding that this has led to an average yield gain of
2.4 bushels per acre.
4
The long game
Pfeffer urges growers to think
beyond the current season when it comes to early weed control. “It’s not just
about maximizing your yield potential in the current growing season. It’s also
about long-term sustainability,” he says. “If you don’t pay attention to weed
control, land values suffer. You can hide poor fertility issues, but with
weeds, it’s obvious things haven’t been taken care of.”
“To me it’s the emotional
connection,” says Pfeffer. “If you have someone you care about, who you want to
leave the land to, you don’t want to leave it in a mess.”
1 https://albertacanola.com/wp-content/uploads/2015/02/2014-3.3-Control-Weeds-Early.pdf
2 results of this research are cited at:
https://cdnsciencepub.com/doi/full/10.1139/cjps-2017-0147, original research
paper is behind pay walls.
3 First flower is when 50% of the plants in the field have no more than one
flower.
4 Source: Bayer Market Development research trials, 2008 – 2014 (n=39).
Average of 2.4 bu./ac. advantage over 2-pass.