Which type of adjuvant increases the viscosity of spray mixtures?

• A. Sticker
• B. Extender
• C. Thickener
• D. Surfactant

Answer: (C)

The concept here is how adjuvants modify the physical properties of the spray, specifically viscosity. A thickener adds agents that increase the liquid’s resistance to flow, so the spray mix becomes thicker or more viscous. This helps the droplets resist shearing and wind drift and helps the coating stay on the target longer after application.

A sticker’s job is to help the pesticide adhere to leaf surfaces and resist being washed off, but it doesn’t inherently raise the mixture’s thickness. An extender increases the carrier volume to improve coverage but doesn’t necessarily make the spray thicker. A surfactant lowers surface tension to improve wetting and spreading of droplets, which can actually make the liquid flow more easily on surfaces rather than thicker.

So, the adjuvant that increases viscosity is the thickener.