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
September 4, 2019 7:55 AM

Sensing an impending lackluster performance by the Cyclone football team, I spent the Saturday of Labor Day weekend touring several Palmer amaranth infestations in western Iowa. This is the 6th year of this trek, the first stop is always Harrison County at the first reported Iowa...

Weeds
August 13, 2019 9:48 AM

The current approach to weed management in Iowa is at risk due to rapid expansion of herbicide-resistant weeds. In order to preserve the efficacy of herbicides two things must happen: 1) adoption of integrated weed management, and 2) shift the goal of weed management from protecting crop yields...

Herbicide Resistance
August 12, 2019 2:28 PM

The 2019 Iowa State University Extension and Outreach Iowa State Fair Weed Identification Contest was held on August 9 outside the John Deere Agriculture Building.  Contestants need to identify live samples of weeds of agricultural, horticultural, and natural habitats in Iowa.  Youth are tasked...

Weeds
July 17, 2019 7:49 AM

Question: If the state and county are so concerned about wild parsnip, why aren’t they out spraying it? The ditches and county roads are full of it.1

...

Weeds
July 17, 2019 6:29 AM


Contestants at the 2018 State Fair Weed Identification Contest

The annual ISU Extension &...

Weeds
June 21, 2019 12:06 PM

Wild parsnip is a biennial that was introduced to North America by the earliest European colonists, it is documented to have been grown in Virginia as early as 1609 as a food crop. In his 1913 book The Weed Flora of Iowa, L. H. Pammel described wild parsnip as ‘common on roadsides in...

Weeds
June 5, 2019 8:42 AM

Corn planting has been start and stop, and generally delayed this spring. In some situations the decision was made to plant and not apply nitrogen, or planting progressed so quickly that UAN (urea-ammonium nitrate solution) and herbicide applications couldn’t keep up with the planters, and now...

Weeds
May 20, 2019 10:00 AM

We have always told extension clients and students that the best tool for identifying an unknown weed is a good book, other than finding somebody who already knows what the weed is.  We never thought much of the early weed ID apps that were developed for mobile devices.  In AGRON 217 (Weed...

Weeds
March 25, 2019 11:18 AM

One benefit of planting cover crops is their contribution to weed management.  While several factors contribute to the inhibition of weeds by cover crops, the physical barrier of cover crop residue on the soil surface is most important.  Research has shown a strong relationship between the...

Weeds
March 21, 2019 4:26 PM

The introduction of Palmer amaranth has the potential to significantly impact Iowa crop production in the future.  But as the saying goes, there’s a silver lining behind every cloud, and Palmer amaranth’s silver lining might just be the Iowa Noxious Weed Law.  

Iowa’s Noxious Weed Law has...

Weeds
March 9, 2019 8:31 AM

Several reports of new resistant traits in the weedy Amaranths were announced recently.  First, Illinois reported two populations of waterhemp resistant to metolachlor and other...

Herbicide Resistance
January 31, 2019 7:09 AM

Recent text from an extension client:  
Mark Licht is telling us to plant 120-140K soybeans.  Tells us why more isn’t cost effective. You tell us 160K 15” rows for weeds.  I wish you all would coordinate your story. The bottom line is net profit which is a holistic concept but every...

Weeds
December 20, 2018 11:03 AM

This is part three of a four-part series originally posted in 2016 on using multiple, effective herbicide sites of action (herbicide groups) at effective rates as part of a long-term weed management system. Read ...

Herbicide Resistance
December 13, 2018 12:36 PM

While herbicide resistance is not a new issue, the rapid increase in multiple resistant biotypes in waterhemp, giant ragweed, and horseweed (marestail) is limiting herbicidal options. A waterhemp biotype resistant to six herbicide groups (2, 4, 5, 9, 14, and 27) was recently identified in...

Weeds
December 11, 2018 12:47 PM

This is part three of a four-part series originally posted in 2016 on using multiple, effective herbicide sites of action (herbicide groups) at effective rates as part of a long-term weed management system. Read ...

Herbicide Resistance
December 4, 2018 8:25 AM

This is part two of a four-part series originally posted in 2016 on using multiple, effective herbicide sites of action (herbicide groups) at effective rates as part of a long-term weed management system. Read...

Herbicide Resistance
November 27, 2018 12:56 PM

This is part one of a four-part series originally posted in 2016 on using multiple, effective herbicide sites of action (herbicide groups) at effective rates as part of a long-term weed management system.

With the stagnant development of new herbicides and weeds seemingly...

Herbicide Resistance
November 1, 2018 7:31 AM

Updated on November 2, 2018

I feel obligated to write something about EPA’s dicamba announcement, but will confess at this time I still have several questions...

Weeds
October 31, 2018 1:05 PM

While the monarch butterfly is a globally distributed species, the eastern United States population is renowned for its annual migration from the breeding range in the northeastern United States (and Canada) to overwintering sites in central Mexico.  Overwintering populations of this cohort have...

Crop Production
September 3, 2018 8:53 AM

It's Labor Day weekend, that means it's time for me to see what's happening at the first three Palmer amaranth infestations in western Iowa. The infestations (Harrison, Fremont, and Page Counties) were first reported in 2013.  Harrison County had two fields (approximately 50 acres) with...

Weeds
August 25, 2018 10:10 AM

The finding of mile-a-minute weed near Knoxville, and the subsequent request for reports of additional infestations, has led to a flurry of calls regarding potential findings. Fortunately, none of the reports have been positive, but we appreciate people paying attention to plants in the...

Weeds
August 15, 2018 12:40 PM

Another contest is in the books, and once again we provided a sufficient challenge to prevent anyone from earning a perfect score.  In the Professional Division, two-time defending champion Cindy Recker was narrowly edged out by Karen Stiles, last year’s winner in the General Division. Both...

Weeds
July 23, 2018 3:36 PM

Mile-a-minute weed (Persicaria perfoliata) is an invasive species in the Polygonaceae (smartweed) family that is native to Asia.  It is believed to have been introduced to the United States in the late 1800’s and early 1900’s, but the initial introductions failed to form permanent...

Weeds
July 9, 2018 9:35 AM

Off-target injury associated with dicamba application in dicamba-resistant soybean was a significant problem in the Cornbelt during 2017 (A final report on dicamba-injured soybean acres).  The increase in...

Weeds
May 18, 2018 8:31 AM

Cool conditions during planting season increase the potential for herbicide injury to seedlings due to slow emergence and reduced ability of the crop to metabolize herbicides. While herbicides may be responsible for emergence issues, most problems that have been brought to our attention seem to...

Weeds

Pages