Aug 9, 2011 by Lee Hart

Things you need to know about weed control

Now here is something you really don’t want in your field.
No, I’m not talking about Kelly Bennett, portfolio marketing leader, cereal
herbicides with Dow Agrosciences (pictured left).

Bennett and Buckwheat .jpeg

I’m talking about the very robust wild buckwheat plant he
is holding. Bennett, a Saskatchewan farm boy who has been with DAS for 25 years, made the very simple
point, during a recent tour of DAS crop protection demo plots – the primary
purpose of your herbicide program is to get rid of weeds like this wild
buckwheat, as well as kochia, cleavers, hemp nettle, lamb’s quarters and
probably a few dozen more common weeds that all can affect crop yields for
Western Canadian farmers. You don’t want this mess robbing yields and snarling
up your combine header.

The program usually starts with a pre-seeding burndown with
a glyphosate product, but then follow that up with the proper in-crop herbicide
treatment. Know your weed spectrum, use the proper product, at the proper
application rate, with the proper timing and then as Bennett demonstrates
(photo at right) more of your weeds are going to look like this instead.

Controlled weed .jpeg

DAS describes themselves as the Solutions People. They are
not just selling chemicals, but weed control solutions. They are putting money
into research and development, field testing and extensive demonstrations to
find products that work and then show producers how well they work, often in
comparison with other leading products.

As Bennett and Len Juras, former Sask Agriculture weed
specialist, who is now a weed scientist with DAS, pointed out on this tour —
there are no silver bullets out there. Glyphosate, when it was first
introduced, was perhaps considered a silver bullet — the big fix for all your
weed problems. Well, it isn’t. It is good and effective in a lot of situations
but it can’t do it all. And just like every other herbicide or chemical on the
market there is concern now about development of glyphosate-tolerant weeds. So
even if one chemistry is good, you just can’t hammer the weeds year after year
with the same product.

NEW APPROACH TO HERBICIDE TOLERANCE

DAS, like other companies, are now developing more dual
action or tandem herbicide products. One objective of combining two products
such as Simplicity and Attain, Simplicity/Frontline/24D, Tandem/24D ester, or Simplicity and a
new version of Attain being called Octtain (registration is in the works), is to cover a wider weed spectrum and give producers more
options. But, perhaps even more importantly is to combine two products with different
chemistry effective on the same weed, to reduce the risk of developing
herbicide tolerance. 

In recent years there has been a lot of emphasis by weed and
chemical people on rotating herbicides — different modes of action — to prevent
herbicide tolerance. Use a Group 2 herbicide this year to control wild
buckwheat, for example, and then use a chemistry from a different group next
year to nail any of those wild buckwheat plants that escape.

Now the preferred thinking is to combine two products so if
a few smart weeds appear to be tolerant to one chemical, the other one will get
them — sort of a one/two punch.

As Juras (pictured below, left) explains, researchers are finding there is a
synergy in combining two products with different modes of action in one
application. If one product is 75 per cent effective in controlling a weed, for
example, and the other product is 80 per cent effective, by combining the two,
producers are seeing 95 or 98 per cent weed control. It is not fully understood
how or why it works, but the main point is that it does work.

Like developing new canola varieties, it is a long process
in developing new herbicide chemistry. DAS has a Discovery Centre in
Indianapolis where they may screen 100,000 different chemistries each year to
find a few that may just have an inkling of potential for controlling a certain
weed. Those few are then introduced into a research program for further testing
in various parts of the world. Duds are booted right away, but with each trial,
any that show greater promise are moved along and measured for every possible
positive or negative impact on the crop or the environment. Getting a chemical
from the Discovery Centre to a fully registered product ready for producers can
easily take 10 years. The cost of the process doesn’t add up quite as quickly
as the U.S. debt, but it is expensive.

Juras and Degenhardt.jpeg

And a final note on weed control — just when you might think

Marsh willow herb.jpeg

 all the bases are covered, something new shows up.In these two photos, Rory
Degenhardt (right), an Alberta farm boy, also a weed scientist with DAS, shows a relatively new weed he’s
found in certain parts of Saskatchewan called Marsh Willow Herb. It is not
difficult to control but it is appearing. It likes bogs (i.e. much of
Saskatchewan this year) but on the upside the leaves are edible. So it affords
itself to an integrated weed control strategy — spray and/or snack.

Lee
Hart is a field editor for Grainews in Calgary, Contact him at 403-592-1964 or
by email at
[email protected]

 

Lee Hart

Lee Hart


Lee Hart is a long-time farm writer, and honorary member of the Alberta Institute of Agrologists, with many observations on the agriculture industry, who never hesitates to admit he is wrong (should that ever happen.)


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