into storage scab lesions after harvest. Disease Cycle and Causal Organism Apple scab is caused by the fungus Venturia inaequalis, which also is capable of infecting crabapple , hawthorn, mountain ash, and firethorn . Different but closely related Venturia...
at prevailing temperatures (table 1), growth from the germinated spore penetrates and infects these organs just beneath the outer cuticle. Typical lesions, each bearing tens of thousands of secondary or summer spores (conidia). appear about 9 to 17 days later...