Resistance Fighter: Ask the Expert

Facts About Recent Waterhemp Discovery in Central Illinois

Chuck Foresman — Fri, 23 Jul 2010 19:17:00 GMT

A waterhemp population in a central Illinois seed corn production field has been found resistant to several commercially available HPPD-inhibitor herbicides. Last year, the field contained waterhemp populations that were not controlled by foliar-applied HPPD-inhibitor herbicides.

Syngenta greenhouse testing has confirmed resistance in this waterhemp population to several post-emergence applied HPPD-inhibitor herbicides including mesotrione, available as Callisto^® herbicide. In addition, Syngenta field studies showed ineffective weed control with post applications of HPPD inhibitors, and ineffective control with post applications of some ALS and triazine herbicides applied alone to the same population.

Syngenta field studies showed that pre-emergence applications of HPPD inhibitors Lumax^® and Lexar^® (containing mesotrione, S-metolachlor and atrazine) provided effective control of this waterhemp population.

As I explained in a news teleconference earlier this week, this particular field was used for seed corn production, and for seven consecutive years there was over-reliance on certain post-emergence HPPD-inhibitor herbicides to control key weeds. Hybrid seed corn production systems often preclude the use of important broad-spectrum herbicides like glufosinate or glyphosate. The lack of diversity in both herbicide modes of action and crop rotation in this field led to the development of resistant waterhemp.

In Syngenta field tests, the following products applied post-emergence also controlled the population: 1) PPO-inhibiting herbicides, available as Flexstar^® and Prefix^® herbicides; 2) certain glufosinate and auxin containing herbicides; and 3) glyphosate, available in Touchdown^®, Flexstar GT and Halex^® GT herbicides. The multiple modes of action in Flexstar GT (fomesafen and glyphosate) and Halex GT (S-metolachlor, mesotrione and glyphosate) work to reduce selection pressure and help delay the onset of weed resistance.

At Syngenta, we are dedicated to sound weed resistance management and took immediate action to understand this non-performance issue, and we are working with the University of Illinois, local dealers and farmers on proper stewardship.

The HPPD-inhibitor technology is important for farmers as they continue to work to meet the demands of an ever growing population. To preserve this important technology, Syngenta recommends proactive resistance management practices including rotating modes of action and crops, using pre-emergence residual herbicides, full herbicide rates, tank mixing herbicides with multiple modes of action, as well as appropriate cultural practices like tillage and cover crops to reduce selection pressure.

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©2010 Syngenta Crop Protection, 410 Swing Road, Greensboro, NC 27409.Important: Always read and follow label instructions before buying or using Syngenta products. The instructions contain important conditions of sale, including limitations of warranty and remedy.

Lexar and Lumax are Restricted Use Pesticides.

Callisto^®, Flexstar^®, Halex^®, Lexar^®, Lumax^®, Prefix^®, Touchdown^® and the Syngenta logo are trademarks of a Syngenta Group Company.

Six State University Study Illustrates Value of Herbicide Diversity

Chuck Foresman — Fri, 16 Jul 2010 13:46:00 GMT

A professor and extension specialist in the crop science department at North Carolina State University, Dr. David Jordan along with his colleagues in weed science, conducts extensive research on weed management practices and directs statewide educational programs. In a recent interview, Jordan discussed his findings related to weed resistance in cotton and shared management recommendations for growers. For more information on his research and additional recommendations, visit the North Carolina State University website.

Syngenta: What weed management studies do you currently have underway with regards to glyphosate resistance?

Jordan: We are currently participating in a six state study on sustainability of glyphosate, or Roundup based systems. This multi-year study, referred to as the Benchmark Study by our group of cooperators, was initiated in 2006 and will be completed after the 2010 season. Farmers were asked to split fields in half and manage weeds as they normally would on one side (considered the farmer side) while on the other side of the field farmers followed university recommendations. In general, university recommendations included additional preemergence or postemergence herbicides and most cases included a wider diversity of herbicide modes of action (MOA.)

Syngenta: What is the goal of the study?

Jordan: One of the goals is to better understand weed population dynamics in glyphosate-based weed management systems. An important second goal is to develop strategies (and extend that information to growers and their advisers) that sustain glyphosate in cotton weed management programs.

Syngenta: Can you tell me how the results in the farmer side of the field differed from the results in the side of the field that incorporated university recommendations?

Jordan: Higher cotton yield and greater economic return were noted on the researcher side for all years even though the herbicide investment was higher. The benefits of increased herbicide input/management on the researcher side manifested in greater economic return, which most likely was associated with reductions in early season weed interference with cotton. Greater diversity of MOAs is important in managing herbicide resistant weed populations in the long term.

Syngenta: How do you think this study will influence cotton advisers and growers in their weed management decisions?

Jordan: Growers often focus on essential issues facing them at the moment, and often times management decisions do not consider long-term impacts. Data from this study indicate that including a greater diversity of herbicides and minimizing early season weed interference is not only valuable in the short term, but most likely will also pay dividends from a resistance management standpoint in the long term.

A professor and extension specialist in the crop science department at North Carolina State University, Dr. David Jordan along with his colleagues in Jordan: Higher cotton yield and greater economic return were noted on the researcher side for all years even though the herbicide investment was higher. The benefits of increased herbicide input/management on the researcher side manifested in greater economic return, which most likely was associated with reductions in early season weed interference with cotton. Greater diversity of MOAs is important in managing herbicide resistant weed populations in the long term.

Syngenta: How do you think this study will influence cotton advisers and growers in their weed management decisions?

Watch out, Louisiana: weeds to keep an eye on

Chuck Foresman — Fri, 09 Jul 2010 13:02:00 GMT

At a recent Syngenta South Delta crop tour in Alexandria, La., participating retailers and consultants learned about potentially dangerous effects of weed resistance and ways to avoid it. As one of the tour presenters, I cautioned participants that though it may not be an impossible issue for the area now, weed resistance has the potential to become one in the near future. Johnsongrass resistance is already becoming a major concern; there currently are 1.2 million crop acres infested with johnsongrass in the state of Louisiana, and glyphosate is not controlling it. Ryegrass is another one I urged participants to watch out for in the area.

As I've written before, the main causes of resistance include cutting rates, improper timing of application, and repeated use of the same herbicide. I reminded tour participants that overlapping weed control options, rotating modes of action and crops, and using full rates are all excellent ways to prevent resistance. Syngenta has some great tools to assist in the resistance management battle, including Dual Magnum^® and Prefix^®. Dual Magnum works really well on ryegrass when applied in the fall, and Prefix is a great option for controlling broadleaf weeds and grasses.

A few of my colleagues also spoke during the tour about ways to control resistance issues in soybeans and cotton. To hear segments of these presentations and to read more about the topics covered during the recent Syngenta crop tour, visit deltafarmpress.com/syngentasfctour/.

Caption: Participants take part in a recent Syngenta South Delta crop tour in Alexandria, La.

©2010 Syngenta Crop Protection, Inc., 410 Swing Road, Greensboro, NC 27409. Important: Always read and follow label instructions before buying or using Syngenta products. The instructions contain important conditions of sale, including limitations of warranty and remedy. Dual Magnum^®, Prefix^® and the Syngenta logo are registered trademarks of a Syngenta Group Company.

Survey shows growers are adopting practices, but there’s still room for improvement

Chuck Foresman — Fri, 02 Jul 2010 17:05:00 GMT

In a recent web poll by AgProfessional.com, which surveyed site visitors from June 9 to June 23, participants were asked "What percentage of your customers are using multiple modes of action to control weeds in their corn fields?"

The poll resulted in a tie, with 20 percent of respondents answering that zero to 20 percent of their customers are using multiple MOAs and 20 percent answering that 21 to 40 percent of their customers are using multiple MOAs..

Although the responses of these ag professionals does indicate that some of their customers have recognized the need for non-glyphosate modes of action on their fields and have adopted the practice, it is clear from this poll that we still have a long way to go.

The use alternate modes of action and the incorporation of residual herbicide applications into a weed resistance management program not only offers extended activity on problem weeds, it also helps growers protect the value of glyphosate and its future effectiveness on all weeds, whether currently glyphosate resistant or not.

Caption: Photo above compares treatments of glyphosate 7 DAT versus Halex® GT 28 DAT.

So tell me, how would you have responded to this poll?

©2010 Syngenta Crop Protection, Inc., 410 Swing Road, Greensboro, NC 27409. Important: Always read and follow label instructions before buying or using Syngenta products. The instructions contain important conditions of sale, including limitations of warranty and remedy. Halex® and the Syngenta logo are registered trademarks of a Syngenta Group Company.

New Uses for "Old" Chemistry in Resistance Management

Chuck Foresman — Thu, 24 Jun 2010 16:13:00 GMT

Glyphosate resistance has been all over the national news recently. Articles have brought to light the serious threat resistance poses to production agriculture, to many in the general public, which is quite alarming in the context offered. What the mainstream media fail to mention is the viable and safe practices being recommended by weed scientists and industry experts and adopted by growers across the nation to successfully combat glyphosate resistance.

At a recent plot tour in Mt. Olive, N.C., local retailers were able to see how some "old" chemistry being incorporated into resistance management programs performed in field trials. When used in conjunction with Prefix or Flexstar^® GT, Boundary^® (a premix combination of metribuzin and Dual Magnum^®) and Sequence^® (a premix combination of Touchdown Total^® and Dual Magnum) provided excellent control of several difficult-to-control weeds, including glyphosate-resistant Palmer pigweed.

To build a customized weed management program for your fields, visit the Resistance Fighter Solutions Module.

©2010 Syngenta Crop Protection, Inc., 410 Swing Road, Greensboro, NC 27409. Important: Always read and follow label instructions before buying or using Syngenta products. The instructions contain important conditions of sale, including limitations of warranty and remedy. Gramoxone Inteon is a Restricted Use Pesticide. Boundary^®, Dual Magnum^®, Flexstar^®, Gramoxone Inteon^®, Prefix^®, Sequence^®, Touchdown Total^® and the Syngenta logo are registered trademarks of a Syngenta Group Company.