Which type of adjuvant acts as a wetting agent and spreader (i.e. alters surface tension of spray droplets)?

• A. Buffer
• B. Extender
• C. Surfactant
• D. Anticoagulant

Answer: (C)

The key idea here is how adjuvants change how spray droplets behave on leaf surfaces. Surfactants act as wetting agents and spreaders by lowering the surface tension of the spray solution. When surface tension is reduced, droplets spread more readily across the leaf’s waxy cuticle instead of beading up. This creates a more uniform coating and improves coverage and potential absorption of the pesticide.

Buffers adjust pH and don’t affect surface tension. Extenders help increase coverage or the duration of coverage, but their main job isn’t to lower surface tension. Anticoagulants have no role in spray wetting or spreading.