Bob Hartzler

Dr. Bob Hartzler is a professor of agronomy and an extension weed specialist. He conducts research on weed biology and how it impacts the efficacy of weed management programs in corn and soybean. Dr. Hartzler also teaches undergraduate classes in weed science and weed identification.

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September 1, 2015 7:29 AM

An extension client asked why waterhemp that survive a postemergence herbicide often develop into a bushy plant with an abnormally thick stem.  The short answer would be the plant was too big when it was sprayed, but I trust this person wanted a more in-depth response.


August 25, 2015 7:50 PM

One of the first memories of my extension career is a farmer from northwest Iowa explaining his approach to managing the weed seedbank. He stated that he carried a box of atrazine 90DF in his combine. Whenever he encountered a velvetleaf or cocklebur he would stop, pull the offending weed, place...

August 24, 2015 1:05 PM

Burcucumber and wild cucumber (AKA wild balsam apple) are weedy members of the cucumber family.  They are frequently found along river bottoms and other wet areas, and may cause serious problems due to their ability to climb and smother small to medium sized trees.  Burcucumber is more likely to...

August 13, 2015 7:23 AM

Wild parsnip is an invasive plant commonly found in roadsides, pastures, restored prairies and other areas with full sun and minimal disturbance.  It is a biennial that forms a rosette with 'celery-like leaves' (Fig. 1.) and an umbel with yellow flowers (Fig. 2).  It contains a class of...

August 10, 2015 8:21 AM

The annual ISU-Iowa State Fair Weed Identification Contest is this Friday, August 14, from 9:00 - 11:00 AM in front of the John Deere Agriculture Building.  With three divisions (Future Agronomists, General, and Professional) it is indeed fun for the entire family.  See how your weed ID skills...

August 10, 2015 7:37 AM

Figure 1.  A poison ivy trifoliate leaf.


In the past few weeks I've had at least five inquiries regarding a...

July 30, 2015 9:01 AM

Proper selection of adjuvants is essential for effective weed control with herbicides.  Unlike herbicides, adjuvants are not regulated - thus anything can be marketed for this purpose and manufacturers are not required to describe the active ingredients.  This leads to the introduction of ...

July 28, 2015 8:40 AM

Most agronomists are aware of the movement of Palmer amaranth into Iowa.  Although known Iowa infestations are limited to five counties (Harrison, Fremont, Page, Lee and Muscatine) we are confident that it is present in many more counties.  We are pleased by the number of people who have...

July 27, 2015 4:14 PM


Fig. 1.  Cutleaf teasel seedheads.