If ester formulations of 2,4-D are used at temperatures above 85 degrees, what risk increases?

• A. Herbicide damage to ornamentals
• B. No risk
• C. Increased weed resistance
• D. Reduced effectiveness

Answer: (A)

Hot weather makes ester formulations of 2,4-D highly volatile, so when used above 85°F they can vaporize and drift off the target area. That increased volatility means non-target plants, like ornamentals near the treated turf, are at greater risk of injury from off-target movement or vapor exposure. So the main risk under these conditions is damage to ornamentals nearby, not lack of risk, weed resistance, or reduced effectiveness on the target weeds. The other options don’t fit because the scenario specifically points to off-target injury from volatility, and high heat amplifies that risk.