PHI stands for Pre-Harvest Interval, and indicates the minimum number of days between application and harvest. Choose the correct unit.

• A. minutes
• B. days
• C. hours
• D. weeks

Answer: (B)

PHI is the time you must wait after applying a pesticide before harvesting to protect people from residues. That waiting period is measured in days because crops and harvest schedules are planned in daily terms, and residue levels change over days. Pesticide labels specify the pre-harvest interval in days (sometimes presented as a number that can be converted to weeks, but the official unit shown is days). Minutes or hours are far too short to reflect how residues decline, and while weeks can represent the same span, the standard labeling unit is days. So the correct unit is days.