An adjuvant used to thicken spray mixtures so they cling to surfaces is:

• A. Surfactant
• B. Emulsifier
• C. Sticker
• D. Buffer

Answer: (C)

A sticker adjuvant is used to help pesticides stay on treated surfaces by forming a sticky film. This film-forming action increases adhesion, so the spray clings longer and is less likely to wash off with rain or irrigation. That’s exactly what you want when the goal is to thickens or hold a spray in place on surfaces, improving coverage and duration of effect.

Surfactants, by contrast, lower surface tension to improve spreading and wetting, which helps the spray cover more area, but they don’t create a lasting film to hold the residue in place. Emulsifiers mix oil and water components and aren’t about sticking to surfaces. Buffers adjust pH and influence chemical stability, not adhesion. So the film-forming, cling-enhancing action of a sticker makes it the best fit for this purpose.