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
May 24, 2016 12:56 PM

While I don't have a bucket list of weeds, it's always nice to find a new one. Today I had my first encounter with blue mustard (Chorispora tenella). Like all mustards, this plant has four petals, but the petals of blue mustard are pink to purple in color and very narrow, relative to...

Weeds
May 20, 2016 9:47 AM

I've had several questions on how long to wait following the frost event this past weekend before making a postemergence application. The answer depends on several factors, including 1) stage of corn at frost injury, 2) vigor of corn at time of frost, 3) weather following the frost, and 4)...

Weeds
May 19, 2016 1:08 PM

While driving to a field plot in Webster County earlier this week I saw a land roller being used in a field. My first thought: "If we have time to roll fields, why is there such resistance to the suggestion of mechanical weed control?"


Most farmers of my age have...

Weeds
May 18, 2016 6:26 AM

Scouring rush and field horsetail are two species in the Equisetum genus. These are primitive plants that produce spores rather than seeds, but they spread primarily by underground rhizomes. Until recently these two weeds were found primarily in roadside ditches, but the reduction in...

Weeds
April 23, 2016 9:48 AM

Had a question why winter annuals, specifically henbit, are so thick this year.  Two main factors: 1) ample moisture at the end of last year's growing season, and 2) a relatively mild winter.  Most winter annuals emerge in late August-September, in many years we don't have enough soil moisture...

Weeds
April 19, 2016 9:49 AM

The focus has been on planting corn, but don't forget about the weeds. In addition to getting preemergence herbicides applied to the corn acres, burndown applications on no-till soybean fields should be a top priority. Timely application of burndown herbicides simplifies controlling many winter...

Weeds
April 9, 2016 12:36 PM

A 'true' weed ecologist probably would have shuddered at my explanation to young 4-H'ers how weeds survive our control efforts:  

1) shake them off (giant ragweed) or 2) overrun them with numbers (waterhemp).


...

Weeds
April 5, 2016 8:13 AM

The rapid spread of herbicide resistant weeds threatens the current Midwest production system. Introduction of new herbicide resistance traits will provide additional management options for resistant-prone weeds such as waterhemp, giant ragweed, and marestail; however, these systems must be used...

Herbicide Resistance
March 16, 2016 10:37 AM

While walking through the Memorial Union a painting caught my eye. The resemblance between Palmer amaranth seedheads and the artwork was striking, my photography skills not so much.


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Weeds
March 13, 2016 7:29 AM

Question: What was the most popular POST herbicide program for corn in Iowa Crop Reporting Districts 1 and 2 (NW and NC Iowa) in 1985?

Answer: 2,4-D + Banvel (dicamba), with 78 and 64% of the acres treated, respectively.

Every time I see an...

Weeds
February 28, 2016 9:11 AM

The overwintering monarch population in Mexico was reported last week and has increased for the second consecutive year (Figure 1). Four hectares of forest (9.9 acres) were covered with monarchs, up from the low of 0.7 hectares in the winter of 2013-14. While this is good news, the low numbers...

Insects and Mites
February 25, 2016 2:23 PM

This is fourth and final part of a series focused on using multiple, effective herbicide groups at effective rates as part of a long-term weed management system.


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Herbicide Resistance
February 23, 2016 9:58 PM

A two-page, print-friendly version of the Herbicide Use May Restrict Grazing Options for Cover Crops is now available to download for free at the Extension Store.

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Crop Production, Weeds, Herbicide Resistance
February 18, 2016 9:20 AM

This is part three of a four-part series on using multiple, effective herbicide groups at effective rates as part of a long-term weed management system.


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Herbicide Resistance
February 11, 2016 9:44 AM

This is part two of a four-part series on using multiple, effective herbicide groups at effective rates as part of a long-term weed management system.

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Herbicide Resistance
February 4, 2016 9:23 AM

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

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Herbicide Resistance
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...

Weeds
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...

Weeds
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...

Weeds
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.


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Weeds
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...

Weeds
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...

Weeds

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