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
June 22, 2017 11:04 AM

The introduction and spread of Palmer amaranth in Iowa undoubtedly will have a significant impact on crop production and weed management in the future.  However, since the first infestations were identified I've been intrigued by what seemed odd behavior for a plant with Palmer amaranth's...

Weeds
June 21, 2017 12:33 PM

The six weedy Amaranthus species at the weed garden have grown quite a bit, but I'm not sure how much easier it is to differentiate a few of the species. The six pigweeds are Palmer, Powell's and spiny amaranth, waterhemp, and redroot and tumble pigweed (not in that order!!). The...

Weeds
June 13, 2017 7:55 AM

This year at the ISU FEEL weed garden I've established a plot with nine weedy members of the Amaranthaceae family, including six pigweeds .  The pigweeds were transplanted on June 9 and pictures taken on June 11. Species include redroot pigweed, tumble pigweed, Palmer amaranth, spiny amaranth,...

Weeds
June 8, 2017 2:19 PM

While searching for Palmer amaranth in a pollinator habitat planting I encountered a few musk thistles.  As I always do when I see this weed, I examined flower heads for the presence of the musk thistle weevil.  This insect was imported to North America as a biocontrol agent for musk thistle.  ...

Weeds
May 12, 2017 3:43 PM

I decided to take advantage of the great weather and see if Palmer amaranth could be identified in CRP fields where it was introduced last year.  I went to one field in Boone County and another in Story County.  I was happy to find that both fields had good stands of forbs that will compete with...

Weeds
May 1, 2017 2:49 PM

CCA diagnosing corn root problemsAn online review course is being offered through Iowa State University...

Crop Production
May 1, 2017 11:11 AM

There are several challenges to controlling Palmer amaranth in CRP, including:

1)  Most infested CRP fields used seed mixes containing native forbs and grasses.  Controlling the Palmer while preserving the forb component will be difficult, if not impossible.

2)  Group 4 herbicides...

Weeds
April 18, 2017 12:27 PM

Iowa State University Extension and Outreach is helping Iowa farmers manage weeds, insects and diseases in their fields.

Pest management is key to high yields and quality grain. ISU Extension and Outreach specialists are working to provide the tools and resources farmers need to manage...

Insects and Mites, Plant Diseases, Weeds
April 17, 2017 3:54 PM

A common question regarding cover crops is will interception of preemergence herbicides by the cover crop reduce the activity of the herbicides. If this was a consistent problem, it would make sense to apply the preemergence herbicide in a separate application from the burndown after much of the...

Weeds
April 13, 2017 1:03 PM

Two Canadian weed scientists1 recently published a paper ranking their top 10 herbicide-resistant weed management strategies.  The following is my paraphrasing of their list:

10)  Accurate recordkeeping
  9)  Strategic tillage
  8)  Site-specific weed management...

Herbicide Resistance
April 10, 2017 10:27 AM

The primary impact of herbicide resistance for most Iowa farmers has been an increase in expenditures for herbicides.  I decided to do a quick analysis of this by using ISU Extension’s annual Estimated Costs of Crop...

Weeds
March 12, 2017 12:52 PM

Since I inducted the FeXapan advertisement into the Herbicide Ad Hall of Shame for proclaiming to be the answer to resistance, I feel obligated to do the same with TeeJet's recent ad in Wallaces Farmer.  Proper nozzle selection is critical for:  1) minimizing off target...

Herbicide Resistance
March 9, 2017 11:33 AM

ISU's student newspaper recently published a story on Dr. Ada Hayden, the first woman to earn a Ph.D. from ISU (...

Weeds
March 6, 2017 1:12 PM

A bill has been introduced in the Iowa legislature that proposes classifying Palmer amaranth as a primary noxious weed.  The weed law gives counties the authority to fine landowners who fail to control noxious weeds, and, if necessary, enter...

Weeds
February 26, 2017 8:13 AM

It has been several years since I’ve added anything to the Herbicide Ad Hall of Shame, but I feel DuPont’s sales sheet for Fexapan warrants inclusion.  At a time when nearly everyone realizes we are painting ourselves into a...

Herbicide Resistance
February 12, 2017 9:47 AM

The University of Illinois Plant Clinic recently published results of their 2016 herbicide resistance screening program.  For a $50 fee the Clinic analyzes...

Herbicide Resistance
February 11, 2017 11:09 AM

Planning on attending the Commodity Classic in San Antonio in March?   Have experience with herbicide resistant weeds?  

If you are involved in crop production in Iowa, the answer to the second question is yes.  The Weed Science Society of America is sponsoring a listening session at the...

Herbicide Resistance
January 20, 2017 1:30 PM

I've been asked several times at meetings this winter if it would be possible to identify Palmer amaranth in conservation plantings at this time of year.  My response has been 'I think so, but I've never tried'.  To avoid having to use that answer in the future, I went to a field planted to...

Weeds
January 15, 2017 8:43 AM

I recently had a discussion with a farmer regarding the Palmer problem, and he asked if I were 'King for a Day' how would I change Iowa's noxious weed law.  I came up with four suggestions regarding classifying weeds as noxious:

1)  Eliminate any weed from the list that is widely...

Weeds
December 29, 2016 8:22 AM

People involved in weed management for at least 20 years probably remember corn being damaged by glyphosate drift when Roundup Ready soybean were first introduced.  The extensive damage was due to the high susceptibility of corn to glyphosate; equipping sprayers with low-drift nozzles and the...

Weeds
December 22, 2016 7:56 AM

The recent approval of the new dicamba products approved for use on Xtend soybean has been received with mix feelings by the agricultural community; many are excited about the new options to help with the growing herbicide resistance problem, whereas others are concerned about the risks...

Weeds
December 12, 2016 7:34 AM

The 2017 version of WC 94 - Herbicide guide for Iowa corn and soybean production - is now available.  The guide includes several tables providing information on herbicide effectiveness, composition of package mixes, and herbicide sites of action.  In addition the guide...

Weeds
December 5, 2016 9:29 AM

I’ll admit it, I enjoy the laughing weeds in Syngenta’s Acuron advertisements. The Acuron Chronicles remind me of something written by Dutch Sylwester more than 60 years ago.  Dutch was ISU’s extension weed scientist from 1945 to 1975, and his...

Weeds
October 17, 2016 6:26 AM

One of the more popular pages on the old ISU Weed Science website was the Herbicide Ad Hall of Shame. It featured ads that I deemed went against Integrated Pest Management (IPM) principles. Recently, two of my colleagues nominated the attached ad that promotes the effectiveness of dicamba in...

Weeds
October 7, 2016 1:57 PM

A grower provided us a sample of the seed mix used on one of the conservation plantings where Palmer amaranth developed following planting. We were able to extract Amaranthus seed from the native seed mix. Since it is difficult, if not impossible, to visually differentiate the ...

Weeds, Herbicide Resistance

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