Taking the “Scare” Out of Resistant Weeds

Halloween. Ghosts, ghouls, goblins, mummies, witches, zombies and monsters. Scary? Naah. I’ll tell you what’s scary. Weed resistance! Want to hear a farmer cuss? Listen to him/her say the word Kochia, Waterhemp, or Marestail. Judging by the tone they use to say it, you are pretty sure it is a cuss word.


These yield-robbing, noxious weeds are hard to get rid of.   When harvesting, it is easy to see the path a Kochia (a.k.a. tumbleweed) has taken as it tumbled across the field, blown by the wind, scattering seeds in its wake to take root. And when that tumbleweed comes to rest in the fence line, it generously continues to spread its seeds. A single waterhemp plant can produce over a half a million seeds. Controlling these resistant weeds is of major concern to soybean growers.

In the early days of soybean growing, a kid could make some extra money “walking the beans” for soybean farmers. Of course, if your dad was the farmer, the making money part was iffy. Hand pulling was the best practice to control weeds that resisted tillage and herbicides. Tillage practices were changed to conserve our topsoil and soil moisture, and then Roundup was introduced. When Roundup came on the market, it made us all good farmers because weeds were killed, crops weren’t harmed and the cost of the weed control was only $10-$15/ acre. But then weed resistance reared its ugly head and continues to pressure our fields.   Using a 50-50 corn, soybean rotation is one way growers deal with resistant weeds. Limiting field disturbances of tractors, animals, or people through infested areas helps decrease the spread of resistant weeds. Cleaning out fence lines is useful as well. But, even with all of these efforts, resistant weeds are a “growing” problem.

If controlling resistant weeds is an issue you are dealing with, it is critical get a management plan in place. Harvest is the perfect time to analyze how your weed management program is working. Continuing with the same program you have been using, if it isn’t effective, is just throwing good money after bad.

Research says utilizing multiple effective herbicides is needed. Each tillage practice needs an appropriate herbicide program to manage weed pressure. Relying on a single technology, herbicide, or class of herbicides are methods that helped bring us into our current resistant situation. The use of residual herbicides, following label directions, and timely application are key steps in helping manage herbicide resistant weeds. In addition, looking for soybean varieties that produce a canopy sooner can also cut back on competition from weeds. Vigilance in controlling weeds that show resistance has become a foremost mission for soybean growers.

Liberty Link technology in soybeans and Liberty weed control programs have worked well for some growers. Using a premix before planting and then following up with Liberty post planting might be part of an alternative weed control program.

Roundup Ready 2 Xtend soybeans contain the Genuity Roundup Ready 2 Yield trait technology stacked with a trait containing dicamba (a particular herbicide) tolerance which allows for control of some resistant weeds. Yield results that we have seen of Roundup Ready 2 Xtend (RR2X) in our area this fall have been terrific.

Halloween and harvest season go hand in hand. Harvest exposes the success and failures of our management programs. It’s also the season for purchasing seed for next year. Treat yourself. Analyze your weed resistance concerns now, make a weed control plan and use it as you make your cropping decisions for next year. The success of RR2X this year and the potential it offers as part of your resistant weed management strategy has created high demand for this new product. Act now. Don’t let “spooky” weeds get the best of your crops in 2017.

Image Credit: Troy Williams

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