GCC Custom Applicator Jake Drohman pours in an adjuvant to combine in his spray application mixture while treating weeds on pre-emergent corn.  Photo by Trevor Hands. 

When it comes to spraying your fields, adjuvants are a critical part of an effective application.  There are many different types of adjuvants, each with their own jobs.  Many products can often contain multiple adjuvants, which makes it super convenient and efficient to load but also carries a risk of using the wrong product.  With the multiple cominations that exist out on the market today, knowing what they all do ensures you select the right one for the right job and don't end up having to spray a second time - or lose your crop's yield potential or the crop completely.


Most adjuvants can be grouped into four major categories:

               • Surfactants

               • Oils

               • Water Conditioners

               • Drift Reducing Agents


SURFACTANTS - Most common used are Non-ionic Surfactants.

               • Reduce surface tension of the plant

               • Act as a wetting agent

               • Spread the droplet on the leaf, increasing surface area, delivering more active ingredient to the target



               • Act as spreaders

               • Help penetrate waxy coatings on the leaf cuticle


       PETROLEUM-BASED OILS - Crop Oil Concentrates (COC's)

                    • Made up of highly refined petroleum-based oils

                    • 15-20% Surfactants or Emulsifiers


       SEED-BASED OILS - Methylated Seed Oils (MSO's) 

                    • Made up of Soybean, Cotton, Canola and Sunflower Seed Oils

                    • 5-10% Surfactants or Emulsifiers

                    • Great for tougher conditions:  low humidity, high temperatures, larger weeds



                    • Higher rates of Surfactants and Emulsifiers in combination with Crop Oils

                    • Allow for higher activity at half the rate - (1/2 gallon of crop oil per 100 gallons of water as opposed to conventional at 1 gal / 100)


WATER CONDITIONERS - Reduce the reaction of hard water ions

               • Many wells in our area have hard water which makes the chemistry involved in spray applications not perform properly.                 

               • Many chemicals such as Glyphosate need a water conditioner.

               • Most common used is Dry Ammonium Sulfate (AMS).

               • Many liquid forumlations exist, although some of them do not include AMS.

               • Make sure you know what your requirements are for your application as many chemicals require a certain amount of AMS to be effective.  


DRIFT REDUCING AGENTS - (DRA's)              

               • Reduce off target drift on spray solution by reducing the amount of driftable fines (or the volume of the spray that is made up of droplets smaller than a certain size, i.e. 150 microns) in the spray pattern.     

               • Increase spray deposition by increasing the amount of droplets within the target area.         

               • While DRA's can help reduce drift, they can only be helpful to a point.  Only spray when the wind is in the right direction and is of reasonable strength.  Drifting on a neighbor's field can be costly! 


It is imperative to read and follow label directions.  These products have been meticulously tested, been proven to be effective and deemed safe to use within the confines of their intended usage and precautions advised.  As the old saying goes, "The most expensive spray job is the second one."


At the Garden City Co-op we carry a large selection of adjuvants that are proven winners.   Contact your local sales manager & agronomist for more information at 620-275-6161.