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How Iowa is Facing Herbicide Use Challenges

By: Dr. Charles Benbrook, Science Team Member

I had an opportunity to attend and speak at two meetings in Iowa on May 14-15, 2018. On the 14th in Iowa City, “Pesticides and Public Health in Iowa: 2018 Networking Meeting” was sponsored by Iowa State University Extension, the University of Northern Iowa’s Center for Energy and Environmental Education, and the Great Plains Center for Agricultural Health.

Access my presentation here, and through the Resources section of this website.

The next day in Ames at that city’s lovely public library, I was the main speaker at a workshop entitled “Managing Weeds for Healthy Kids: Emerging Challenges for Physicians, Families, and Farmers.”

In Ames, I presented an overview of the issues leading to the Managing Weeds for Healthy Kids project. I discussed new data emerging from ongoing biomonitoring efforts, and highlighted key new science on herbicide health risks that also is described on this website, for example:

  • Mills et al. (2017) on rising levels of glyphosate in human urine;
  • Parvez et al. (2018) documenting GLY in the urine of more than 90% of pregnant women and a possible link to preterm delivery; and
  • McBirney et al. (2017) reporting that the widely used herbicide atrazine triggers heritable, epigenetic changes in a three-generation rat model.

The Ames prezi is accessible here, and by request, it is also posted as a video (~25 minutes to view).

Presented by Dr. Benbrook in Ames, IA on May 15, 2018. Click image to view in new window.

Please feel free to draw on these presentations if helpful in your work. We are also glad to share any of the underlying analytical work and references, most of which are accessible via this website.

The meetings were attended by individuals working for Iowa state agencies, universities, and research institutions. Several farmers attended, as well as NGOs and concerned citizens.

A similar set of questions arose during the Q+A periods — “what can Iowans do?” to assure that rising herbicide use does not trigger an increase in the number or severity of reproductive problems and birth defects. Flying back west the next day, I thought about this key question and offer these additional suggestions:

  • The Iowa Department of Public Health should carry out, or partner with an ongoing research project, to monitor levels of herbicides used widely in Iowa in the urine of a cross-section of Iowans, with special focus on pregnant women and infants, and the big three herbicides — glyphosate, 2,4-D, and dicamba (“big” because use is rising so fast).
  • The Iowa Department of Agriculture or ISU should annually release a detailed accounting of herbicide use on the major crops grown in the state, along with trend data back to 1990 – the year USDA started collecting detailed pesticide use data by state.
  • State agencies and Iowa universities should join together in calling on the seed-biotech-pesticide industry to significantly increase the share of the corn and soybean seed supply that does not contain genes rendering the crops resistant to herbicides.

Dr. Matt Liebman first used the phrase “many little hammers” to describe integrated, ecological weed management in the 1990s.

Herbicide use data on major Iowa crops should be widely accessible in a relational database, including county-level estimates building on the data periodically issued by the USGS.

Easy access to such data, the more detailed the better, would help scientists studying the linkages between herbicide use and public health or environmental outcomes.

The Need for “Many Little Hammers”

Nearly everyone in the weed management world, including most farmers, understand that corn and soybean production systems in Iowa must become less reliant on herbicides, and especially glyphosate, by integrating “many little hammers” back into Integrated Weed Management systems.

As I made this point at the close of my talk in Ames, I was pleased to acknowledge in the audience one of the co-authors of the 1997 paper that first used the phrase “many little hammers.”

This approach to weed management was a primary focus of ISU’s Dr. Matt Liebman and colleagues at the University of Maine in the 1990s, and was featured in the book Ecology in Agriculture (published in 1997).  In a chapter co-wrote with Eric Gallandt entitled “Many Little Hammers: Ecological Approaches for Management of Crop-Weed Interactions,” Matt and Eric lay out the essential attributes of sustainable weed management systems that can increase on-farm profit margins and lighten agriculture’s environmental and public health footprint.

This might be a good time to dust off the 1997 paper, and related papers in section 4a of this website, to gain deeper insights into what happens when weed management systems become excessively reliant on just one big hammer.

1 Comment

  • My sister in PA sent me a link to this article. It’s ironic because I live less than 10 miles from Ames and have been drifted with pesticides three times now this year alone. The latest was just today at noon. We get drifted every year, but seems it gets worse every year. We have replanted our windbreak 3 times, but usually there is little material damage. The applicators love the fact that little material damage is usually done. It lets them focus on the material loss and not on the bigger picture. We have spent 10 years working very hard to establish our families chemical free gardens, fruit groves and chickens. Even though the sprays didn’t kill anything they have left us feeling very frustrated and angry that what we value – growing and eating chemical free food – has zero material value when assessing damages. And since the State’s politicians have exempted the applicators from any legal liability, there is very little one can do. I am considering suing in civil court or even trying to muster up a class action lawsuit. I am sure there is a pattern of neglect or disregard for the law.

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