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Postemergence Applications in Enlist and Xtend Soybean (06/20/19)

Postemergence herbicide applications have been in full swing for much of the state over the last week.

Postemergence herbicide applications have been in full swing for much of the state over the last week. Some questions have been rolling in about herbicide applications made in Enlist and Xtend soybean. Here are some of the more frequent questions and associated answers as of June 18th, 2019:

 

Q1: What products can I tank-mix with Enlist One, Enlist Duo, Engenia, Fexapan, Xtendimax, or Tavium?

Each of these products has a website of any and all approved tank-mix partners. This includes other herbicides, fungicides, insecticides, adjuvants, and anything but water. These websites are updated frequently as more products become approved for use. The websites should be checked within 7 days of making an application to see which products are approved for use.

 

Q2: I know I can’t use AMS with the dicamba products, what about Enlist One or Enlist Duo?

Certain AMS-containing products are approved for use with Enlist One and Enlist Duo. There is no blanket prohibition on using AMS with these two herbicides. However, the product must be approved and listed on the tank-mix websites. At this time, not all AMS-containing products are approved for use.

 

Q3: Dicamba and 2,4-D are both Group 4 herbicides that kill broadleaf weeds. Are these soybeans tolerant to both dicamba and 2,4-D?

No they are not. Enlist soybeans are still highly sensitive to dicamba-containing products. Dicamba soybeans are sensitive to 2,4-D containing products. A new publication from my colleagues at Purdue walks through the visual symptoms to expect from 2,4-D or dicamba exposure in non-tolerant soybean (https://ag.purdue.edu/btny/weedscience/Documents/WS-56.pdf).

 

Q4: What about growth stage cutoffs or calendar date cutoffs?

For the 4 approved dicamba products, we have 3 cutoff stages to watch for. The federal labels for Xtendimax, Fexapan, and Engenia state that applications must end 45 days after planting, or when soybeans reach the R1 growth stage. Tavium has a growth stage cutoff of V4 soybean (instead of R1). In addition, North Dakota has a calendar date cutoff for all 4 dicamba products that states that the last application must end 2 hours before sunset on June 30th. Both Enlist One and Enlist Duo allow application through (but not later than) the R2 growth stage of soybean. At this time, there is no calendar date cutoff in place for either Enlist product. Please see Dr. Hans Kandel’s article in last week’s Crop and Pest Report to see anticipated arrival of these soybean growth stages based on planting date and GDD accumulations so far this season.

Joe Ikley

Extension Weed Specialist

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