3 benefits of a two-pass herbicide system

Hard-to-control weeds like Palmer amaranth, marestail and waterhemp wreak havoc on your corn and soybean fields – robbing your crop of essential resources and reducing yield potential. The threat of weed resistance has made it more challenging for farmers to effectively control weeds with a one-pass system. Ron Geis, market development specialist with Corteva Agriscience, said farmers who stick to a one-pass system may limit their ability to control tough weeds. 

“When you do everything in one shot, whether that’s a pre- or postemergence herbicide application, you’re putting all your eggs in one basket,” Geis said. “The problem there is you’re relying on everything – planting time, application time, weather – to go perfectly. I encourage farmers to implement a two-pass program with pre- and postemergence herbicides because it reduces risk, delivers better weed control and helps keep plants healthy in the long term.” 

Risk mitigation 

Timing is crucial to a successful weed control program, especially when using residual herbicides. If you don’t receive adequate rainfall after application, herbicides may not activate properly. Similarly, if rains come too late, weeds may already have emerged, reducing control. Then, too much rain can prevent you from making any herbicide application at all. 

With a two-pass system, your fields are less vulnerable to weather variability. A preemergence application provides initial weed control, while a postemergence application adds a second layer of control to help ensure proper management, even if Mother Nature doesn’t cooperate. Additionally, planning for a second application can help optimize inputs, whereas relying on a rescue application can create a domino effect of setbacks. 

“A weed management program that features both a pre- and postemergence application will help weatherproof your operation,” Geis said. “This allows farmers to not be under the gun to get weed control out there before the weeds get away from them. Similarly, if you have a two-pass system and Mother Nature throws a curveball that could then cause an insect or disease outbreak, farmers can address that issue in-season with a tank-mix of crop protection solutions as they make their second herbicide pass.”

Improved weed control 

A preemergence herbicide application followed by a postemergence herbicide application can provide better, more consistent control of tough weeds all season long. A single pass can fail under heavy weed pressure, a wet spring or other environmental factors. 

Geis recommends starting with a strong preemergence herbicide, such as Resicore^® REV herbicide in corn or Sonic^® Boom herbicide or Kyber^® Pro herbicide on soybean acres to reduce early weed competition and get long-lasting residual control. A residual product is key to achieving cleaner fields longer. For postemergence products, consider Kyro^® herbicide for corn or Enversa^™ herbicide for soybeans.  

“We can’t raise two crops in the same field at the same time,” Geis said. “A crop of weeds is one you don’t want competing with your corn or soybeans. With a two-pass system, you’re able to start clean and stay clean.”

To strengthen control further, Geis suggests including Enlist One^® herbicide in the tank for crops with the Enlist^® trait. This adds another mode of action to help you manage weeds during both pre- and postemergence applications and combat weed resistance. With more than 1,700 qualified tank-mix partners available, Enlist One herbicide can easily fit into a variety of agronomic programs. Visit EnlistTankMix.com for tips and a full list of tank-mix partners. 

Healthier plants

Weeds can impact crops in more ways than one. In addition to competing for nutrients, weeds can serve as alternative hosts for harmful insects and diseases, including white mold, soybean cyst nematode (SCN) and more. Effective weed control is critical for limiting insect and disease carryover and reducing the weed seedbank – helping support healthier fields season after season. 

“Properly managing weeds will help you protect your fields from threats and safeguard yield potential,” Geis said. “The sooner you are able to eliminate weeds, the better it is for your crop yield potential and field health.” 

For more information about a two-pass herbicide program, visit Corteva.com/us or contact your local Corteva Agriscience representative. 

Following burndown, Enlist Duo^® and Enlist One^® herbicides with Colex-D^® technology are the only herbicides containing 2,4-D that are authorized for preemergence and postemergence use with Enlist^® crops. Consult Enlist^® herbicide labels for weed species controlled. Enlist Duo and Enlist One herbicides are not registered for use or sale in all states and counties; are not registered in AK, CA, CT, HI, ID, MA, ME, MT, NH, NV, OR, RI, UT, VT, WA and WY; and have additional subcounty restrictions in AL, GA, TN and TX, while existing county restrictions still remain in FL. All users must check “Bulletins Live! Two” no earlier than six months before using Enlist One or Enlist Duo. To obtain “Bulletins,” consult epa.gov/espp/, call 1-844-447-3813, or email ESPP@epa.gov. You must use the “Bulletin” valid for the month and state and county in which Enlist One or Enlist Duo are being applied. Contact your state pesticide regulatory agency if you have questions about the registration status of Enlist^® herbicides in your area. ALWAYS READ AND FOLLOW PESTICIDE LABEL DIRECTIONS. IT IS A VIOLATION OF FEDERAL AND STATE LAW TO USE ANY PESTICIDE PRODUCT OTHER THAN IN ACCORDANCE WITH ITS LABELING. ONLY USE FORMULATIONS THAT ARE SPECIFICALLY LABELED FOR SUCH USE IN THE STATE OF APPLICATION. USE OF PESTICIDE PRODUCTS, INCLUDING, WITHOUT LIMITATION, 2,4-D-CONTAINING PRODUCTS NOT AUTHORIZED FOR USE WITH ENLIST CROPS, MAY RESULT IN OFF-TARGET DAMAGE TO SENSITIVE CROPS/AREAS AND/OR SUSCEPTIBLE PLANTS, IN ADDITION TO CIVIL AND/OR CRIMINAL PENALTIES. Additional product-specific stewardship requirements for Enlist crops, including the Enlist Product Use Guide, can be found at www.traitstewardship.com. Enversa^™, Kyber^® Pro, Kyro^®, Resicore^® REV and Sonic^® Boom are not registered for sale or use in all states. Enversa, Kyro and Resicore REV are not available for sale, distribution or use in Nassau and Suffolk counties in the state of New York. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. Consult the label before purchase or use for full details. Always read and follow label directions.