What best describes the mode of action of fungicides used to control dollar spot?

What best describes the mode of action of fungicides used to control dollar spot?

• A. They are all systemic inhibitors that move throughout the plant.
• B. They act exclusively as surface protectants with no systemic effect.
• C. They can be fungitoxic or fungistatic; some are systemic inhibitors while others are contact protectants; rotation is advised to avoid resistance.
• D. They have no effect on dollar spot when used alone.

Answer: (C)

Fungicides can work in more than one way. Some are fungitoxic, meaning they actively kill the fungus, while others are fungistatic, simply inhibiting the fungus’s growth. In dollar spot management, you’ll encounter products that move systemically inside the plant (systemic inhibitors) and products that stay on the surface to block infection (contact protectants). Because these fungicides have different modes of action, rotating among them helps slow or prevent the pathogen from developing resistance. That combination of having both systemic and contact options, with the possibility of fungicidal or fungistatic effects, and the need for rotation to avoid resistance, is why this option best describes how fungicides used to control dollar spot work.

Fungicides can work in more than one way. Some are fungitoxic, meaning they actively kill the fungus, while others are fungistatic, simply inhibiting the fungus’s growth. In dollar spot management, you’ll encounter products that move systemically inside the plant (systemic inhibitors) and products that stay on the surface to block infection (contact protectants). Because these fungicides have different modes of action, rotating among them helps slow or prevent the pathogen from developing resistance. That combination of having both systemic and contact options, with the possibility of fungicidal or fungistatic effects, and the need for rotation to avoid resistance, is why this option best describes how fungicides used to control dollar spot work.