What type of adjuvant is used to increase the viscosity of spray mixtures?

The choice of a thickener as the correct answer is based on its specific role in altering the characteristics of a spray mixture. Thickeners are substances added to the formulation to increase viscosity, which helps to prevent the spray solution from drifting away from the target area during application. This attribute is particularly important in pest control applications where precision is essential to ensure effective targeting of pests while minimizing potential environmental impact.

While surfactants are commonly used to improve the spreading and wetting properties of solutions, they do not primarily focus on increasing viscosity. Emulsifiers help stabilize mixtures of oil and water but are not intended to thicken formulations. Adhesives are used to improve the sticking ability of pesticide formulations to surfaces but do not play a role in modifying the viscosity of the liquid. Thus, thickeners are integral for creating the right consistency for effective application in pest control scenarios.