Glyphosate Formulations

Mark VanGessel, Extension Weed Specialist;

With increased glyphosate costs and the limited availability of glyphosate this year, you may be looking to buy brands that you are not familiar with. Here are a few things to keep in mind when buying glyphosate.

There are numerous products containing glyphosate in the marketplace, but there is no consistency in how the companies report what is contained “in the jug”. Glyphosate is what kills the plant and it is an acid molecule, but it is formulated as a salt for packaging and handling. Various salt formulations include isopropylamine, diammonium, monoammonium, or potassium. Some brands include more than one salt.

Some companies report their product as acid equivalent (ae) of glyphosate acid, or some report it as active ingredient (ai) of glyphosate plus the salt, and others report both. In order to compare performance of different formulations it is critical to know how the products were formulated. Since the salt does not contribute to weed control and different salts have different weights, the acid equivalent is a more accurate method of expressing, and comparing concentrations.

Adjuvant loading refers to the amount of adjuvant already added to the glyphosate product. Fully loaded products contain all the necessary adjuvants, some contain no adjuvant system; while other products contain only a limited amount of adjuvant (minimal or partial loading) and additional surfactants must be added to the spray tank before application. Refer to product labels for specific recommendations. Most glyphosate brands recommend adding ammonium sulfate (AMS) if using hard water as a carrier or under other challenging conditions. If using AMS, always dissolve it in the spray solution before adding glyphosate.

Finally, some products will support technical service for the performance of the product and others come with no technical support. Usually the lower cost products have limited to no technical support.

So when trying to decide on which formulation of glyphosate to buy, be sure you know:

  • the glyphosate concentration (how much product to add)
  • adjuvant load (whether you need to add any surfactant and how much)
  • whether the product will be “supported” by a technical rep of the dealer or manufacturer

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