How do you like your coffee? So strong it could revive a dead cat? Straight up black? A nice glug of milk? Or do you prefer coffee in your glass of milk? I personally only drink coffee if I’m cold or have a migraine – a specific condition.

The combination of metribuzin, sulfentrazone, glyphosate and MSO did not control the cover crop. (Photo provided by Karen Corrigan)

Just as people like their coffee, a certain way to kickstart their day – herbicides need specific surfactants to perform at their best.  They may accept other surfactants as needed – just as many would drink any coffee as opposed to no coffee, but it won’t put them at the top of their game.

Why is this important? Using the correct surfactant for an herbicide will make it more likely to control the targeted weeds. Some herbicide failures can be avoided if the correct surfactant is used. An example this spring was a tank mix of metribuzin, sulfentrazone, glyphosate and MSO used to terminate a cover crop and lay a residual for the soybeans. The combination of the residual herbicides and MSO burned the weed leaf tissue so quickly that the glyphosate never entered the plant. The cover crop had necrotic tissue but did not actually die, causing a need for a second application to achieve control. The proper surfactant to use with glyphosate for optimal performance is NIS, nonionic surfactant.

Have you experienced issues controlling volunteer corn in soybeans with an ACCase Inhibitor herbicide (clethodim, sethoxydim, quizalofop, fluazifop)? Did you use COC, crop oil concentrate? Herbicides like clethodim work better with COC, particularly if the volunteer corn is tall. Ever tried to use glufosinate without the proper AMS, ammonium sulfate? If not, DON’T. You won’t be impressed.

Some surfactants increase crop injury. Herbicide labels will specifically say NOT to use surfactants due to the increased likelihood of crop injury.

If the crop/weeds are under drought or stress conditions, the label may increase the rate of surfactant under this specific circumstance to use to achieve more uptake and control.

In a tank mix, it can be difficult to use the proper surfactant for each component. This is something that should be taken into consideration when planning a tank mix. Choose products that are enhanced by the same surfactants, or at least not negatively affected by them.

Read the herbicide labels. If you’re looking for more information on surfactants or adjuvants in general check out the Crop Protection Network article: “Adjuvants with Herbicides: When and Why They are Needed”

The left side has MSO. Middle isn’t overlap. Right side has no MSO. Only the right side achieved control. (Photo provided by Karen Corrigan)

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About the Author: Karen Corrigan

Karen Corrigan, an independent agronomist and co-owner of McGillicuddy Corrigan Agronomics, offers specialized agronomic consulting services to farmers in the upper Midwest. With a focus on improving production practices, Karen excels in weed science and fundamental agronomy. A Certified Crop Adviser in both Illinois and Iowa, she holds a master’s degree in agronomy-weed science from the University of Wisconsin-Madison. Karen is the incoming chair for the Illinois CCA Board, showcasing her leadership in the field. As an instructor at Heartland Community College, she teaches classes on agronomy, soils, horticulture, and pest management. In collaboration with friends Kelsey Litchfield and Jen Campbell, Karen hosts the monthly podcast, Girls Talk Ag. Karen is a Tazwell County Master Gardener and volunteers by giving seminars to patrons and by helping to stock their free seed libraries. She is a member of the McLean County Farm Bureau and serves as the Community Outreach Chair. Karen is the leader of the McLean County STEAM Team 4H club. Karen is also a mom of two elementary aged girls, two doodles, and a tiny rescue dog.

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