What is the primary reason to know a product's mode of action?

• A. To rotate chemistries and manage resistance.
• B. To reduce application cost.
• C. To speed up harvest.
• D. To improve color.

Answer: (A)

Knowing a product's mode of action tells you how it affects a pest at its biological target, which lets you plan rotations of products that act differently. Rotating chemistries reduces the chance that pests with resistance to one action will dominate, because survivors from one tool are suddenly hit by another that works in a different way. This helps maintain effectiveness over time and extends the useful life of products, reinforcing good resistance management and stewardship. The other options don’t address why MOA knowledge matters: avoiding resistance isn’t about lowering costs, speeding harvest, or improving color, and those factors aren’t driven by how a product disrupts a pest’s biology.