What defines the economic injury threshold in turfgrass pest management?

• A. The density of pests at which the cost to manage the pest is equal to the losses caused by that pest.
• B. The density at which damage becomes visible.
• C. The density at which all pests are eliminated.
• D. The density at which beneficial insects die.

Answer: (A)

The economic injury threshold is all about cost-benefit in pest management. It’s the pest density at which the economic losses from pest damage equal the cost of taking control. At that point, applying treatment justifies the expense because it prevents losses that would be at least as high as the control cost. If you’re below that density, the cost of treatment would exceed the damage prevented, so you’d hold off; if you’re above it, treating provides a net economic benefit.

In turfgrass, this means you’re aiming to act before damages become financially devastating, but not so early that control costs outweigh the benefits. The other ideas—damage being merely visible, trying to eliminate all pests, or harming beneficial insects—don’t capture the decision point where control costs balance expected losses.