Scab fungus on apple and flowering crabapple overwinters in which location?

Scab fungus on apple and flowering crabapple overwinters in which location?

• A. On Fallen Leaves
• B. In Soil
• C. In Bark Crevices
• D. On Fruit

Answer: (A)

Overwintering inoculum for apple scab is found mainly in fallen leaves. The fungus survives the winter in infected leaf litter as structures that release spores when spring rains return and the leaves wet. Those spores then infect new leaves and shoots, driving the disease early in the season. This is why sanitation—removing and destroying fallen leaves—is such an effective cultural control. The other locations listed are not the primary wintering sites for this pathogen, so they don’t serve as the main source of inoculum as the growing season begins.

Overwintering inoculum for apple scab is found mainly in fallen leaves. The fungus survives the winter in infected leaf litter as structures that release spores when spring rains return and the leaves wet. Those spores then infect new leaves and shoots, driving the disease early in the season. This is why sanitation—removing and destroying fallen leaves—is such an effective cultural control. The other locations listed are not the primary wintering sites for this pathogen, so they don’t serve as the main source of inoculum as the growing season begins.