Page 35 - 2019 Ag Mag

KMAland 2019 Integrated Pest Management 35

Weed Resistance in Iowa 2015: Meeting of
state-wide leaders
regarding resistance
threat
1950 1960 1970 1980 1990 2000 2010 2020 2017: State-wide
IPRMP program
implementation
begins; Palmer
No resistance 2013: Palmer 2016: Palmer amaranth is
issues; elds were Herbicide use Herbicide amaranth found in CRP added to Iowa
tilled began resistance found in mixes planted noxious weed list
observed
Harrison County throughout Iowa
both corn and soybeans, in southwest Harrison presence of the weed ing. This plan laid out a
weed resistance ad- County, the area where and to combat its spread. detailed program to deal
vanced rapidly as crop- I farm. This weed has with pest resistance in
ping agriculture used the a rapid growth rate, is The plan to protect Iowa.
same herbicide mode of very competitive, is very Iowa crops I observed that Palmer
action, year after year, in prolific in seed produc- In January 2015, I was amaranth plants were al-
both these crops. I called tion and has a proven invited to a meeting in lowed to go to seed in
this issue “too broad of ability to quickly evolve Ames, Iowa, that aimed southwestern Harrison
application.” This broad resistance to herbicides. to deal with resistance of County in 2016, further
application strategy led Because of these char- all pests impacting Iowa spreading this challeng-
to the use of herbicides acteristics, this weed cropping agriculture. ing weed. It was later
when they weren’t nec- has a history in southern Evidence was presented, determined that Palmer
essarily needed, a strat- states of negatively im- showing that not only amaranth also spread
egy that resulted in weed pacting crop production were weeds resistant to across Iowa inadvertent-
species developing a re- with lower yields, higher herbicides, but insects ly due to its presence in
sistance to herbicides at costs or both. My in- too had begun to devel- CRP seed in 2016. Palm-
an alarmingly fast rate. volvement with pest op resistance to insecti- er amaranth was not yet
In August 2013, a resistance really started cides, and plant diseases listed as a noxious weed
very tough and resilient with this incident, as I to fungicides. The Iowa in Iowa, allowing it to ar-
weed called Palmer ama- helped then to organize Pest Resistance Manage- rive unnoticed. I started
ranth was first discov- some meetings to make ment Plan (IPRMP) was the dialogue to include
ered growing in Iowa farmers aware of the an outcome of this meet- Palmer amaranth as a