Considerations for Making a Second Postemergence Herbicide Application

Your customer had a good burndown, put out a preemergence herbicide application with a residual component at planting, has a good stand of soybeans and made a postemergence herbicide application to control an initial weed flush, but difficult, and possibly resistant, weeds like marestail, Palmer amaranth and waterhemp are now germinating. Does your customer need a second postemergence application? Here are some factors you might consider to help customers determine if a second postemergence application should be made: 

• New Emerging Weeds, Weather and Escapes
  Keep in mind some weeds germinate and emerge throughout the growing season. Excessive rains or dry conditions with increasing temperatures could limit the effectiveness of that first postemergence application. When dry conditions are coupled with rising temperatures, weeds “harden off” or go into a defense mode to protect themselves from stress — making them more difficult to control. A second postemergence application in better weather conditions will likely yield better results in this scenario. Also, if the application does not fully cover the targeted weeds, escapes are likely. Do not let escapes get so tall they could limit herbicide effectiveness, possibly allowing uncontrolled weeds to go to seed. Curb increases in the seedbank.  
• Herbicide Resistance, Field History and Timing
  The development of herbicide resistance continues to expand across growing regions and should always be considered when evaluating weed escapes, especially when the lack of control is seen in one weed species. Having multiple species of weed escapes may more likely be related to the application being affected negatively by weather, application timing or an issue with herbicide selection. Refer to past scouting and/or control application records. If certain fields have a history of heavier weed pressure, a second postemergence application may be warranted to achieve optimum weed control. The timing of a second postemergence application should be done soon enough to target new emerging weeds but not so late as to interfere with the crop’s growth. Applications made early in the day, when temperatures may be cooler, are less stressful for weeds and crops alike. This can improve herbicide uptake by weeds and allow the crop to metabolize the herbicide easier, reducing the chance of crop injury. 

Your customers make a significant investment in their soybean crop each season. To protect that investment from weeds that can rob water and nutrients from young soybeans, design a herbicide plan with a program approach, which also can lead to improved weed control during critical crop growth stages. 

A herbicide program approach should include a pre- and postemergence herbicide application, as well as a residual product to extend that barrier of protection against developing weeds.

Enversa^™ herbicide can deliver a residual barrier for extended control of more than 20 tough weed species in soybeans. With the encapsulated active ingredient acetochlor, this Group 15 mode of action provides powerful control of glyphosate- and ALS-resistant weed varieties. Enversa offers great handling and tank-mix compatibility for many other partnering crop protection options.

“With a tank-mix including Enversa herbicide and Enlist One herbicide, farmers get great in-tank compatibility, layered residual control and crop safety for their Enlist E3 soybeans,” says Jeff Moon, market development specialist, Corteva Agriscience. “Tank-mixing also allows farmers to optimize their weed control program while helping to mitigate the spread of resistance and extend the overall life of herbicides.”

For more tips, listen to this Brownfield Managing for Profit episode.

The transgenic soybean event in Enlist E3^® soybeans is jointly developed and owned by Corteva Agriscience and M.S. Technologies L.L.C. 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^™ is not registered for sale or use in all states. Enversa is 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. Always read and follow label directions.