Which of the following pesticides is NOT among those described as highly volatile?

• A. Atrazine
• B. Dicamba
• C. Clomazone
• D. 2,4-D ester

Answer: (A)

Volatility is about how easily a pesticide vaporizes and can drift in air. Pesticides described as highly volatile readily form vapors that can move off-target, especially under warm, sunny conditions.

Atrazine has a relatively low vapor pressure, so it does not vaporize easily and is not described as highly volatile. The others in the list are known for greater vapor-drift potential: dicamba can volatilize and drift as a vapor, and the ester form of 2,4-D is more volatile than its other forms, increasing the chance of off-target movement. Clomazone is less volatile than those two, but the key point here is that atrazine is not among the highly volatile pesticides.