Red flags indicate conventional crop fields in the Flag the Tachnology program that helps prevent misapplication of herbicide to nontolerant crops

Red flags indicate conventional crop fields in the Flag the Tachnology program that helps prevent misapplication of herbicide to non-tolerant crops.

Arkansas welcomes Texas and Oklahoma to the pigweed party!

Arkansas weed specialist explains low tech option to differentiate herbicide tolerant fields

I recently presented our Flag the Technology program to the consultants and farmers gathered at the Texas Plant Protection Association annual meeting in College Station. 

I appreciated the opportunity to share this program in Texas. Flag the Technology is our effort to help prevent misapplication and reduce problems with herbicide drift. This program uses a uniform colored flagging system to denote what herbicide tolerance a field has. For example, white flags denote Roundup Ready; green is Liberty Link; and red flags denote a conventional field. We recently added Xtend and Enlist technologies in preparation for their release. If you are interested in this program you can find more information at Flag the Technology.

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I think my visit was well timed. I watched as the university and industry guys talked about the recent discovery and difficulties that Texas and Oklahoma farmers have had with glyphosate resistant Palmer pigweed.  It reminded me of where we were in Arkansas 6 or 7 years ago. Unfortunately, we now have documented pigweed populations that have multiple resistance to glyphosate, the ALS chemistry (Staple/Classic), the PPO chemistry (Valor/Flexstar) and even the DNAs (Prowl/Treflan), leaving us with limited options. For example, in soybeans I expect a lot of Dual, Zidua and Metribuzin use to go along with Liberty; these are the only herbicides left to which we have not documented resistance in Palmer pigweed.

One thing that was eerily familiar was the attitude that many at the meeting had towards pigweed. For example, very few growers I talked to were interested in talking about switching to Liberty Link cotton or soybean. We are now close to 100 percent Liberty tolerant cotton and we expect to increase to close to 50 percent of our soybean acres. This is mostly not by choice but out of necessity. 

It seems that Treflan and a cultivator are working pretty well for growers in Texas Panhandle cotton production. This is great news.  When we developed resistance to glyphosate, our pigweed was already resistant to Treflan.  Instead of Treflan we turned to Reflex applied pre-plant and Liberty in season; in soybean we relied heavily on Valor applied pre and post applications of Flexstar to stay in Roundup Ready systems. The result is now resistance to these PPO herbicides. 


We are now on the verge of relying heavily on Liberty, so we have the real possibility of resistance to it looming on the horizon.

What I hope growers in Texas and Oklahoma can take away from the Arkansas/Mid-South experience with pigweed is that there is no single solution. A diversified approach in terms of herbicide programs, a willingness to change technologies in order to rotate herbicides, and a zero tolerance policy for escapes to deplete the seed bank are some things we wish we could have done years ago when the problem first emerged.

A single escaped pigweed can produce over 1 million seed. Run that through a combine or cotton stripper and you can easily seed the remainder of the field. We have studies that have shown that in as little as 3 years if nothing is done a field can go from one plant to completely grown up in resistant pigweed if production practices are not changed.

From what I saw presented at the TPPA meeting, there is still time to adjust herbicide programs and effect change in the further development of resistant pigweed in Oklahoma and Texas. If you are seeing resistance do not ignore it. If everything is working great, change it! 

Everywhere we have battled pigweed so far it seems that we have underestimated this weed. Do not make this mistake. It is an incredibly genetically diverse, highly competitive and prolific weed. It can reproduce in a few weeks or over the course of an entire summer; it is prone to the development of resistance and just a few escapes can hurt yields and cause major infestations the following year.

I believe pigweed resistance moved rapidly from field to field in Arkansas through harvest equipment. We went from none in 2006 to a statewide problem by 2010—it can happen fast. So do not wait to take some action on your farm. We have some good information on pigweed control at the website listed above. You can also follow me on twitter at @BobScottWeedDr.

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