Soybean Weed Control Starts with the Seed

03:35PM Jul 20, 2018
Weed control options are needed.
( Sonja Begemann )

In 1996, Roundup Ready soybeans revolutionized the way you could farm. Weed issues became virtually non-existent, herbicide programs were cheaper and yields soared. But all good things come to an end and glyphosate resistance finally emerged, bringing with it yield loss, more expensive herbicide bills and weedy, ugly fields.

As new and growing weed resistance looms, it’s important to know your options, especially in soybeans. While herbicide-tolerant trait packages have revolutionized farming in the past, their benefits can quickly fade with improper use.

Today’s weed control options in soybeans include: Roundup Ready 2 Yield soybeans, Roundup Ready 2 Xtend soybeans and LibertyLink soybeans. New products pending approvals are Enlist E3 soybeans, GT27 soybeans and MGI soybeans.

“The most driving weed control needs are on the soybean side because we have so many herbicide options in corn,” explains Duane Martin, Syngenta commercial traits manager. Think about it, waterhemp, marestail, Palmer amaranth are all broadleaf weeds, and broadleaf herbicides have always been available in corn.

New soybean traits

“I planted 100% corn this year just to avoid dealing with the headache of weeds in soybeans,” says Tim Reinhart, Illinois corn and soybean farmer. “We’re going to try one of the new soybean traits next year to use chemicals that have been fabulous in corn.”

While research is underway to find new herbicide modes of action that could be accompanied with a trait, they are years from commercialization—if ever found. With that in mind, it’s critical to protect traits and herbicides so they last as long as possible. 

Start with the seed decision. “Growers need to consider their weed problems when selecting herbicide-tolerant seed,” says Rex Liebl, BASF global product development, herbicides. “When you look at the principles of integrated weed management, one of the most important elements is to mix or rotate modes of action, so you’ll have the option to use something different the second year on your troublesome weeds.”

Overuse of a small handful of herbicides, or a single herbicide, increases risk of resistance. For example, if you use glyphosate in soybeans and again in corn, you could be giving resistance a foothold in your fields.

“It’s all about how you put a weed control plan together,” says Arlene Cotie, Bayer senior development manager. “It’s the herbicide use pattern that creates herbicide-resistant weeds, not the traits.”

More herbicide options with new traits

Resistance has been around since the 1960s, long before the invention of any kind of herbicide tolerance or native or biotech traits.

“I’m younger than some of these herbicides, but not by much,” says Mark Dahmer, Corteva Agriscience technical portfolio strategy leader. “I wish I could tell you how long the current and upcoming chemistries will last but we just can’t. The real issue is how we manage each field, each weed and any escapes. That is what will determine the herbicide, and herbicide trait’s, durability.”