In turf IPM, what is the purpose of economic thresholds, and how are they used to guide management decisions?

• A. The pest density at which action should be minimized to reduce costs
• B. The pest density at which there is observable damage
• C. The pest density at which economic injury would occur without management
• D. The pest density at which action should be triggered to prevent economic loss

Answer: (D)

In turf IPM, the main idea is to use action levels that tell you when to start management so you don’t lose money to pest damage. This action level, called the economic threshold, is the pest density at which you should initiate control to prevent economic losses.

The economic threshold is set well before the point where damage would become costly (the economic injury level). It’s a proactive trigger based on the costs of damage, the cost and effectiveness of control, and the value of the turf. When scouting shows pest numbers at or above this threshold, applying control is expected to be cost-effective, preventing the density from reaching the level where damage would equal or exceed the cost of control.

So the best choice captures that idea: the pest density at which action should be triggered to prevent economic loss. It’s not simply the moment you observe damage, nor the purely damage-based or purely cost-minimization notions, and it’s distinct from the economic injury level, which is the damage-equivalence point if no action is taken.