Agronomy Talk


Herbicide and Weed Management Briefs

Published on Friday, November 5, 2021


There is a difference between residual activity and soil activity. Residual herbicides typically suppress weeds from germinating for four to five weeks. Examples include: Authority®, Valor®, Fierce®, and Zidua®. Products that have soil activity can suppress weeds for 7 to 14 days but will not have enough activity to prevent future flushes of weeds later in the season. Engenia® and XtendiMax® can suppress the germination of small-seeded broadleaf weeds such as waterhemp, but we must pair Engenia and XtendiMax to achieve satisfactory weed control.


The goal of weed management is to make it to canopy closure, but relying solely on the soil activity from dicamba will not make it. Pairing Engenia or XtendiMax with an approved pre-emerge herbicide will help complement dicamba’s soil activity. Many of the pre-emerge herbicides have poor or no burndown activity. Pairing Engenia or XtendiMax can help increase burndown activity, especially on marestail and giant ragweed. When applied in-season, Engenia or XtendiMax can provide up to 14 days of protection against future germinating waterhemp.



Beck’s Practical Farm Research (PFR)® data shows that pairing Enlist One® with Liberty® will result in greater than 95% control of emerged waterhemp. Enlist One + Liberty is a very effective tool for glyphosate-resistant weeds such as waterhemp/Palmer amaranth, marestail, and giant ragweed. However, Enlist One will not have the soil activity of Engenia® or XtendiMax®. Therefore, pairing Enlist One + Liberty with a residual herbicide is crucial. Just like Engenia or XtendiMax, pairing Enlist One with an approved pre-emerge herbicide will help increase the burndown activity of the pre-emerge herbicide. When applying Enlist One + Liberty in-season, pair Enlist One + Liberty with an approved in-season residual to protect from future flushes of weeds.


PFR data showed a significant difference between the soil activity of Enlist One and Engenia at 28 DAT. Engenia had a 37% waterhemp control advantage over Enlist One, but started to break by 28 DAT, showcasing why Engenia still needs to be paired with the proper residual at the correct timing.




Early on, Engenia® soil activity had a significant advantage over Enlist One®. However, by 45 DAT, Engenia’s soil activity fell below 60%. Enlist One + Liberty® has been shown to provide greater than 95% control of emerged waterhemp. However, this tank-mix should be paired with an approved residual herbicide. Though Engenia provides soil activity, it must also be paired with an approved residual herbicide for season-long control.

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Jim Schwartz

Jim Schwartz

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