The order in which a herbicide and other ingredients are added into a spray tank can have a serious effect on the performance of a herbicide application. Proper mixing order ensures incompatible products do not gel or form precipitates that can clog/ruin spray equipment and/or antagonize one another resulting in decreased in weed control. The best way to determine the proper mixing order for spray products is to consult the product labels. However, in the past, acronyms have been helpful guides (e.g., W-A-L-E-S). Based on several current mixing order recommendations, an updated acronym (A-W-A-M-L-E-S) is described below.
Fill CLEAN tank ½ to ¾ full with water or other carrier. If an inductor is used, rinse it thoroughly after each component is added. Add compatibility agent and/or defoamer.
A – Ammonium sulfate (AMS) only products, continue agitating tank
*A product that includes AMS + a surfactant premixed will typically be added last
W – Water dispersible products (wettable powders (WP), dry flowables (DF), etc.)
*Make a slurry with water and then add slowly to tank
A – Agitate tank until all water-soluble products are in solution
*This will take a few minutes
M – Microcapsule suspension (ME) and other suspensions
(suspension concentrate (SC), aqueous suspension (AS), etc.)
L – Liquids that are soluble (SL)
E – Emulsifiable concentrates (EC)
S – Surfactants [nonionic surfactant (NIS), crop oil concentrate (COC), methylated seed oil (MSO)]
Many products available!
Read the label.
More ingredients does not always equal a superior product.
Add remaining water and continue agitation throughout application.
Misha R. Manuchehri
Weed Science Extension Specialist