Which form of 2,4-D is a butoxyethyl ester used as an aquatic herbicide?

• A. Dimethyl amine salt (Clean Amine, Amine 4, DMA4)
• B. Butoxyethyl ester (Aqua-Kleen, Navigate)
• C. Ethyl ester
• D. Alcohol salt

Answer: (B)

The key idea is recognizing the specific chemical form of 2,4-D used for aquatic weed control. The butoxyethyl ester form is designed for aquatic environments because its ester structure makes it less soluble in water than salt forms, allowing it to persist long enough in the water to be taken up by aquatic plants. Once inside the plant, the ester is hydrolyzed to the active 2,4-D acid, producing the herbicidal effect. Products marketed as Aqua-Kleen or Navigate use this butoxyethyl ester formulation, which is distinct from other forms like salts or different esters that serve other applications.