Under favorable conditions, when do plants typically weaken or die after endothall application?

• A. Within minutes
• B. After two weeks
• C. After a month
• D. Plants begin to weaken and die within 3-5 days after application

Answer: (D)

Endothall is a contact aquatic herbicide, so its effect comes from immediate tissue damage where the plant is exposed. When conditions are favorable—warm water, good mixing, and adequate light—the chemical quickly disrupts plant cells and the injured tissues deteriorate, leading to death of the treated plants within a few days. Because the process requires time for the tissue damage to manifest as visible weakening and death, it’s not minutes after application, nor does it take weeks or months. The typical and most accurate timing is within 3 to 5 days after application.