Which pesticide formulation is likely to clog nozzle screens?

• A. Ultra low volume
• B. Soluble powders
• C. Wettable powders
• D. Emulsifiable concentrates

Answer: (C)

The key point here is that nozzle screens clog from solid particles in the spray mixture. Wettable powders are dry, very fine particles that don’t dissolve in water; they stay as a suspension and can form fine clumps or dust that flow through the system and lodge on or in the nozzle screens. That tendency to carry solids and resist complete dissolution makes them the most likely to clog screens during mixing, pumping, and spraying.

Other formulations are liquids or fully dissolve in water, so they don’t contribute solid material that sticks to screens as readily. Emulsifiable concentrates are liquids that form emulsions in water, which minimizes solid buildup at the screens. Soluble powders dissolve, so once fully mixed they aren’t producing solid debris, though incomplete dissolution can still cause issues. Ultra low volume products are also liquid concentrates designed for very small droplets, not solids clogging screens.