At the recent UGA Weed Science Update (12/06/23), Cale Cloud from Grady County asked me if I could talk about herbicide adjuvants. Since I had my talks already prepared, I did not have the time to go into this interesting and very important topic. Here are few things for you to consider:
1) There are numerous adjuvants in the market. Thus, almost impossible for UGA weed scientists to adequately test all of them. I could have spent my whole career just testing adjuvants.
2) Generally, adjuvants can be put into 3 categories including non-ionic surfactants (NIS), oils [crop oil concentrates (COC) or methylated seed oils (MSO)], and fertilizers [usually dry or liquid ammonium sulfate (AMS) or liquid urea-ammonium-nitrate (UAN)].
3) All POST herbicide labels will have a section on recommended adjuvants.
4) Generally (not always), COC/MSO adjuvants will cause more crop injury and provide slightly better weed control than NIS adjuvants.
5) Many COC's are actually made from petroleum oils while MSO's are made from vegetable oils (soybean or sunflower). Both types contain 80-85% oil + 15-20% surfactant. High surfactant oil concentrates (HSOC) contain at least 50% oil + 25-50% surfactant.
6) In my own herbicide testing program, I routinely use Induce (NIS) or Agri-Dex (COC) from Helena unless somebody asks/provides something special. For over 25 years, both of these have worked just fine for me.
Induce: https://s3-us-west-1.amazonaws.com/agrian-cg-fs1-production/pdfs/Induce_Label1g.pdf
Agri-Dex: https://s3-us-west-1.amazonaws.com/agrian-cg-fs1-production/pdfs/Agri-Dex_Label1i.pdf
7) Historically, North Dakota State University (NDSU) has been one of the leading land-grants that regularly tests herbicide adjuvants. I included some very good information about adjuvants from the 2023 NDSU Weed Control Guide (W253-23) in the e-mail that I sent to you regarding this specific blog. This info would make a great edition to your "truck" reference materials.
2023 NDSU Weed Control Guide (https://www.ndsu.edu/agriculture/sites/default/files/2022-12/223214_Weed_Color.pdf)
8) Another good resource for herbicide adjuvants is the Compendium of Herbicide Adjuvants. This publication used to be updated yearly but is no longer. The latest edition (2016) can be found at the following web-address: https://mssoy.org/uploads/files/herb-adjuvants-purdue-siu.pdf
9) If someone is using an adjuvant in your county that you would like to see researched more thoroughly, I can try to fit it into my testing program. This may or may not happen given my time and space constraints.
