Page 11 - 2019 Ag Mag

KMAland 2019 11

marestail and giant ragweed that apply selection pressure with a years. It will allow us to use com-
have developed resistance and/ given herbicide mode of action binations of herbicides in addi-
or enhanced tolerance to various and a population can evolve or tion to residual based herbicides.
herbicides. adapt to survive the application. Also, critical to the fight against
The official global catalog of In fact, for some modes of action resistant weeds is the manage-
weed resistance is at the Weed with certain weed species the re- ment tactics of row spacing, cov-
Science web site: http://www. sistance mechanism is inherent in er crops, mechanical and hand
weedscience.org/Details/Recent- the population, it just takes time labor to remove weeds present in
Cases.aspx Below is a chart of for the weed population to find a fields. Cleaning up weed escapes
resistant weed species for several niche, and then to increase and is critical to long term success.
herbicides sites of action. The thrive. We need to move to a zero-toler-
increasing trend of herbicide re- So, what are we doing about all ance approach.
sistance is happening globally to of this? Companies continue to For the Iowa corn and soybean
many weed species, and multiple search for new and novel modes grower weed management is like
herbicide modes of action. You of action. We are seeing the ad- “Whack A Mole”. We are forced
can also click on the US Map on dition especially in soybeans and to adjust herbicide and cropping
the weed science web site. From cotton of the new traits: Dicamba rotations. We must continue to
that you will note for Iowa, we Tolerance, HPPD Tolerance, 2,4- rely on the residual based herbi-
have 17 confirmed resistant weed D Tolerance, stacked with current cides used in a preventative fash-
species. traits of Roundup Ready and Lib- ion. We then need to manage the
The problem of weed resis- erty Link. Some of these “stacks” weed population and apply our
tance is neither new or likely go- are on the market and some will post, or second application based
ing to change. We consistently likely be available in the coming on the proper weed timing or