Weed Control In Non-GMO Soybeans

 

In some markets, non-genetically modified organism soybeans are bringing $1 or more per bushel than genetically modified (GMO) soybeans.

 

Weed control is a hesitation South Dakota farmers have when making a decision to plant non-GMO seeds in 2017 to take advantage of this potential premium.

 

"Many farmers wonder if it is possible to continue no-till farming practices and plant non-GMO crops with resistant weeds growing in their fields. The answer is 'yes,'" said Gared Shaffer, SDSU Extension Weeds Field Specialist. "With a little more homework producers can control weeds and keep their soil healthy."

 

 

Weed control basics remain the same in non-GMO versus GMO fields, Shaffer explained.

 

1. Begin with a weed-free field at planting

 

"This means, do not plant unless the weeds prior to planting are controlled," Shaffer said. "I cannot stress this enough with any crop, but you need to start with a clean field before planting."

 

To accomplish this, Shaffer encourages the use of a burndown herbicide before or at planting. He recommends a burndown herbicide which provides a broad spectrum of weed control such as glyphosate, paraquat, glufosinate(Liberty®). Other herbicides that may aid in weed control could include 2,4-D ester and a metribuzin product.

 

2. Pre and post herbicide applications?

 

Applying pre-herbicides prior to planting gives farmers some time for a post application, as well as providing soybeans with a head start. "If needed a combination of burn-down with pre-herbicide could be used for extra control" Shaffer said.

 

"If needed, farmers can also apply a post-herbicide when weeds are less than 4 to 6-inches tall after soybean emergence," Shaffer said.

 

The timeline for this may be anytime between two to six weeks after soybean emergence.

 

"The biggest decision here, is to choose herbicides that will provide a window to control early weeds and give the beans a head start," Shaffer said.

 

Examples of pre-herbicides for control depending on weed pressure, could include: Authority Assist®, Authority First®/Sonic®, Canopy®, Valor XLT®, Gangster®, Metribuzin, Python®, Scepter® and Valor®.

 

As for post-herbicide control, Shaffer said it is best to control weeds at 2 to 4-inches tall.

 

"If possible don't allow them to reach over 6 inches tall when relying on herbicide control," he said.

 

Also, use a spray volume of at least 15 gallons per acre (gpa) and nozzles that produce medium-sized droplets.

 

Some post-herbicide options include: Flexstar® or Rhythm® + Select®, Fusion®, etc (grass herbicides) + COC or MSO + AMS. Other options could include FirstRate®, Classic® or Synchrony®. If applied at 28 percent, this may improve weed control but also increase crop injury. If necessary and for late emerging weeds, apply Phoenix® or Cobra® three weeks later if troublesome broadleaf weeds exist, add a grass herbicide if late emerging grasses are a problem.