How long after treatment do plants die when using fluridone?

• A. 6-12 months
• B. 1-2 weeks
• C. 1-2 months
• D. 1-2 days

Answer: (C)

Fluridone is a systemic herbicide that works by blocking carotenoid biosynthesis, which protects chlorophyll and helps plants photosynthesize. Without carotenoids, plant tissues are damaged by light, chlorosis appears, and the plant gradually loses the ability to photosynthesize. Because the chemical has to move through the plant’s vascular system and deplete the plant’s energy reserves, death is not immediate. In aquatic plants, you typically see the plant die over a period of about one to two months after treatment. Some species or larger plants may take longer, but a 1–2 month timeframe is the common expectation. Shorter timeframes like a few days or a couple of weeks reflect fast-acting contact herbicides, not fluridone, while waiting many months is longer than usual for this product’s effect.