To control cedar-apple rust, routine sprays on the apple/crabapple host should be applied during which months?

To control cedar-apple rust, routine sprays on the apple/crabapple host should be applied during which months?

• A. January And February
• B. March And April
• C. April And May
• D. June And July

Answer: (C)

Protection relies on intercepting cedar-apple rust spores as they are released in spring and infect young, susceptible apple leaves. The apple/crabapple host is most vulnerable when new growth is unfolding and the tree is flowering, which happens in spring. Applying routine fungicide sprays during April and May lines up with that window, giving the best chance to prevent infections before they establish on the leaves and fruit. Spraying earlier in January–February isn’t useful because there’s no active leaf tissue to protect, and spraying after June–July comes after the infection window has passed, when rust spores have already had a chance to infect. March–April can be useful, but April–May best captures the entire period of leaf emergence and flowering in many regions, providing comprehensive protection.

Protection relies on intercepting cedar-apple rust spores as they are released in spring and infect young, susceptible apple leaves. The apple/crabapple host is most vulnerable when new growth is unfolding and the tree is flowering, which happens in spring. Applying routine fungicide sprays during April and May lines up with that window, giving the best chance to prevent infections before they establish on the leaves and fruit.

Spraying earlier in January–February isn’t useful because there’s no active leaf tissue to protect, and spraying after June–July comes after the infection window has passed, when rust spores have already had a chance to infect. March–April can be useful, but April–May best captures the entire period of leaf emergence and flowering in many regions, providing comprehensive protection.