Protectant fungicides should be applied when?

• A. After infection
• B. Before infection
• C. Only at harvest
• D. Never

Answer: (B)

Protectant fungicides work by preventing infection rather than curing it. They coat plant surfaces or block spore germination, so they must be present on susceptible tissue before the pathogen arrives or before spores begin to germinate. Once infection has started, these products typically cannot stop that established disease, which is why applying them after symptoms appear is not effective. They are intended to protect new growth during periods of disease risk, and they may need reapplication if conditions remain favorable or rain washes them off. That’s why the correct timing is before infection rather than at harvest or never.