Iowa State University


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Bob Hartzler

Extension Weed Specialist and
Professor of Agronomy

1126C Agronomy Hall
(515) 294-1164


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My motto at work: It takes more than herbicides to keep a good weed down.

What I do: My appointment is 55% extension, 10% research, and 35% teaching (or something close to that - the actual % fluctuate based on a number of factors I don't fully comprehend).  The major focus of my extension activities is promoting the adoption of integrated weed management programs for corn and soybeans. My approach is to develop within extension clientele an understanding and appreciation of weed biology and ecology.  Hopefully, persons equipped with this knowledge will be better equipped to design holistic weed management systems and recognize the difficulty in relying solely on herbicides for weed control.   The weed science web page has evolved into a primary outlet for disseminating information concerning weed management.   My goal is to place information on the web that would otherwise be unavailable to growers and others involved in weed management. 

My research program focuses on aspects of weed biology that directly impact efficacy of weed management programs.  I am particularly interested in the impact of weed seed rain on future weed populations and effectiveness of control tactics.   This work has led me to discount the concept of economic thresholds due to the 'cost' of weed seed production on future weed problems.   A recent project investigated various aspects of incorporating cover crops into Iowa's conventional. I also led a project that screened herbicides for selective weed control in African marigold. While I don't think the marigolds will satisfy the quest for a third crop for Iowa agriculture, it would be nice to see several thousand acres of those bright, orange flowers across the Iowa landscape.

One of the more 'interesting' projects I haved worked on  was a survey of common milkweed across Iowa.  Doug Buhler and I decided to conduct this survey after an article appeared in Science expressing concern that the widespread adoption of herbicide resistant crops in the Midwest might impact monarch butterflies by reducing the availability of milkweed.   We decided it would be important to determine how much common milkweed occurred in cropland versus other habitats.   Shortly after we developed our survey protocol an article reporting the potential for Bt pollen to harm monarchs hit the press, and what we thought was going to be an obscure little study suddenly was of considerable interest to many persons.  We documented an approximatley 90% reduction in common milkweed in Iowa crop fields over a 10 year period (1999-2009). This research has been thurst into the spotlight again with the petition to classify the monarch butterfly as an endangered species. The loss of milkweed in its breeding habitat is believed to be one of the factors contributing to the monarch's decline. I will be surveying the Iowa countryside in 2015 to determine the current status of mikweed in the state and investigating how to establish milkweed in non-crop areas in a way that will have the biggest impact on monarch reproduction.

In addition to my research and teaching responsibilities, I began teaching Agronomy 317, Introduction to Weed Science, in 2002.  In 2009 I developed a one hour course on weed identification that is taught both semesters, and I also serve as academic advisor to approximately 30 undergraduates


Where I came from

I’m originally from Ft. Wayne, Indiana, one generation removed from the farm.   The thumbnail at the left is a picture taken in 1932 of my grandfather (on right) and the Sullivan County Extension Agent in a field trial on my mother's farm in southwest Indiana.  So although I grew up selling Converse All Stars at my dad's sporting goods store in Fort Wayne, at least there is a history of family involvement in agricultural research and extension.  After being influenced by my high school biology teacher (Bob Weber) and Earth Day in 1970, I enrolled in forestry at Purdue, but eventually ended up in the Plant Protection major (a precursor of IPM).  After completing my B.S., I was employed by a large tree and ornamental care firm in Atlanta, GA.  After two years of spraying trees for non-existent pests, I returned to academia at Virginia Tech, earning a M.S. in weed science. From there I moved to ISU to work on a Ph.D. while holding a full-time extension associate position. Upon completing my Ph.D., I took a job as Asst. Professor/ Extension Weed Scientist at Penn State University.  I returned to Iowa State in my current position in 1989. I serve on the Board of Directors of the Midwest Invasive Plant Network, an activity that keeps me grounded to my initial interests in biology and the environment.

My motto when I leave work: Give a man a beer and he wastes an hour; teach him to brew and he wastes a lifetime.

Updated March, 2015.

For more information contact:
ISU Extension Agronomy
2104 Agronomy Hall
Ames, Iowa 50011-1010
Voice: (515) 294-1164