Fluridone non-target toxicity is characterized by

• A. Very low rates (<8 ppm) used for selectivity
• B. High toxicity to humans
• C. Damages shoreline plants only
• D. Immediately kills fish

Answer: (A)

Non-target toxicity in this context comes from how selective herbicides work: they are effective only at very low concentrations, which is why fluridone is described as causing selectivity when used at rates under about 8 ppm. At these low doses, the herbicide targets specific sensitive aquatic plants and minimizes effects on many other organisms. The idea is to achieve control of the intended vegetation while avoiding harm to shoreline plants, fish, and humans. If higher rates were used, the risk to non-target species increases, and the treatment could become harmful to more plants and wildlife. So the best description is that non-target toxicity is characterized by these very low application rates that enable selective action.