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.

Bob Hartzler image
December 22, 2015 7:46 AM

Many people have high expectations for the new herbicide resistant traits, but it’s important to remember that these products are not the next “silver bullet” for successful weed management. A group of weed scientists in the eastern United States evaluated glyphosate resistant (GR) waterhemp and...

December 16, 2015 3:30 PM

The new 2016 Herbicide Guide for Iowa Corn and Soybean Production publication provides information on product and management updates, the role of preemergence herbicides in...

Crop Production, Weeds, Herbicide Resistance
December 9, 2015 3:34 PM

Interest in cover crops has dramatically increased due to their many potential benefits. In addition to conservation purposes, cover crops can provide forage for livestock producers. It is important for livestock producers to consider restrictions on labels of herbicides used earlier in the...

Crop Production, Weeds
November 23, 2015 12:22 PM

By: Bob Hartzler
In the past 10 years, herbicide resistance has grown into a significant problem that is limiting the ability of farmers to effectively control weeds. Farmers have relied on simple weed management in the past, but weeds have grown resistant to simple management systems....

Crop Production, Weeds, Herbicide Resistance
September 11, 2015 12:14 PM

All across Iowa, the edges of woods are lined with plants bearing clusters of white flowers.  There's a good likelihood those plants are white snakeroot, a native perennial in the Asteraceae family.   The plant is best known for its role in milk sickness, an ailment responsible for the death of...

September 7, 2015 12:36 PM

Short Version:  493 miles in 12 hours; 2 out of 3 known Palmer amaranth sites well managed; no new infestations found.

Long Version:  I went to the three Palmer amaranth infestations in western Iowa that I am aware of.  This is...

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.