Why should you avoid applying systemic pesticides when turf is under drought stress?

• A. Drought conditions improve pesticide efficacy.
• B. Systemic pesticides are more effective under drought.
• C. Turf stress increases phytotoxic risk and can reduce pesticide efficacy.
• D. Drought improves pesticide performance.

Answer: (C)

When turf is drought-stressed, its water status and cellular functions are already compromised, and this changes how pesticides behave inside the plant. Systemic pesticides move through the plant with the water transport system, so if transpiration and xylem flow are reduced by drought, the chemical may not distribute evenly to all tissues where pests reside. At the same time, stressed turf is more vulnerable to injury from chemicals; the tissues are more susceptible to phytotoxic effects and may not recover quickly from any additional chemical stress. So you end up with lower, uneven pest control and a higher risk of turf damage. That’s why this option is the best choice: turf stress increases phytotoxic risk and can reduce pesticide efficacy. The other statements imply drought would improve performance or safety, which doesn’t align with how drought alters plant uptake, distribution, and tolerance to chemicals.