Know Your Formulation (Part 3) – Water Dispersible Granules or Dry Flowable (DF)

Water-dispersible (WDG) and Dry Flowable (DF) pesticides are both dry formulations. Some of the first dry formulations available were wettable powders (WP), which are very similar. Although not water-soluble, these dry formulations, when mixed in water, can be made sprayable. Wettable powders had some drawbacks, though; the dust they produced when handled created an inhalation hazard, and they caked easily, making pouring difficult. As manufacturing technology became available, it became feasible to create dry formulations such as WDG or DFs, which consist of much larger particle sizes, making them much safer and easier to handle.

Beyond Wettable Powders: How WDG & DF Formulations Are Made

Making these dry formulations begins by milling active ingredients into extremely small particles, which are then mixed with water and/or other ingredients to form a workable paste or slurry. The two most common processes used to create the final product are extrusion and pan granulation. An extruder is essentially a large screw press that pushes the formulated paste through a die, creating a particle of uniform diameter. Pan granulators are large rotating pans set at an angle that form balls from the slurry as the material rolls on the pan. The ultimate size is determined by the angle of the pan and how fast the pan turns, but the resulting output is a fairly uniform range in particle sizes.

📸: BASF employee/Featuring a sample of an extruded WDG formulation: Status^® herbicide.

📸: BASF employee/Featuring a sample of a pan-granulated DF formulation: Drive^® 75DF herbicide.

In addition to being relatively dust-free, WDG or DF products are easy to pour, store, and transport, and if spilled, are easy to clean up.

The Advantages of WDG & DF Products: Dust-Free, Easy Handling & More! 

Because these formulations are not water-soluble, agitation is necessary to keep them in suspension when mixed with water. Since they contain solids, they can be abrasive to nozzles and pumps, and although screen plugging is rare, it can happen. This is usually caused by not allowing adequate time for particles to get into suspension when mixed with water. 

Mixing & Applying WDG & DF Herbicides: What You Need to Know

As dry products, WDG and DF formulations need to be introduced early in the mixing process. Generally, dry Ammonium Sulfate (AMS) is the first thing added to the spray solution, then DF or WDGs go next. Be careful not to dump a large volume of material in at once. This can lead to a large mass of material sinking to the bottom of the spray tank, where agitation may not be the best.

WDG vs. DF Formulations: Key Differences & Mixing Considerations

It is also important to understand that water needs to be the main carrier. Liquid fertilizers do not have enough water in them to adequately disperse WDG and DF formulations. If you are attempting to apply a liquid fertilizer carrier, you are likely going to have to cut the fertilizer with water. Consider conducting a jar test to determine what water-to-fertilizer ratio will work. It is also a good idea to pre-slurry WDG or DF formulations in water prior to adding them to the sprayer.

📸: BASF employee/Featuring Status^® herbicide as an example of extruded WDG formulation and Drive^® 75DF herbicide as an example of a pan-granulated DF formulation. 

Before mixing components, always conduct a compatibility jar test. Always consult respective product labels for specific mixing instructions. The most restrictive label applies.

Always read and follow label directions. Grow Smart, and Status are registered trademarks of BASF. All other trademarks are the property of their respective owners and use of any such trademark does not imply any affiliation with or endorsement by its owner. © 2024 BASF Corporation. All rights reserved.