How long does diquat typically remain in the water column after application?

• A. It leaches into groundwater.
• B. It is immediately degraded by sunlight.
• C. It evaporates from the water surface.
• D. It remains in the water column for 1–35 days after application, unless low organic matter sandy soils take longer.

Answer: (D)

Diquat’s presence in the water column is temporary. After application, it doesn’t stay indefinitely; in most situations it remains for about 1 to 35 days. The shorter end comes with strong sunlight, warmer temperatures, and typical water conditions that promote rapid breakdown, while the longer end reflects slower degradation under less favorable conditions. Environmental factors such as light exposure and water quality drive these changes. In particular, soils with low organic matter and sandy textures can slow degradation, leading to longer residence times in the water column than the typical range. This understanding helps guide monitoring and any necessary water-use restrictions after treatment.