Which herbicide requires a contact time of 20-60 days for effective control?

Fluridone is known for its slow-acting mode of action, requiring a prolonged contact time of 20 to 60 days for effective control of aquatic weeds. This herbicide is a systemic, selective herbicide that interferes with the synthesis of carotenoids in plants, which is essential for their growth and development. Because of its mode of action, it is important for Fluridone to remain in the water for an extended period to ensure that the weeds absorb enough of the chemical to achieve effective control.

The extended contact time allows Fluridone to effectively target and degrade the plants over time, making it particularly useful for managing stubborn perennial aquatic weeds. Its application often includes considerations of water turnover rates and the specific aquatic environment, ensuring that the herbicide remains present to impact the targeted weeds optimally.

Other options may have different characteristics; for instance, Glyphosate acts more quickly but does not have such a long required contact time for effective results. Copper based herbicides typically require much shorter contact times, as they create immediate toxicity to targeted aquatic plants, and Bispyridil-sodium does not share the same duration for effective weed control.