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This study was carried out to elucidate the resistant factors against apple rot disease such as the anatomic differences of lenticel and the inorganic substance contents between resistant and susceptible cultivars. The apple fruits were infected with the mycelia of Botryosphaeria dothidea through the lenticel tissues under natural condition. The fruit of Fuji, one of very susceptible cultivars had larger numbers of lenticels with more than twice bigger individual size, with higher lenticel cracking percentage, and thinner parenchyma layer under lenticel hole than that of Jonathan, the resistant cultivar. The contents of inorganic matter in fruit skin and fruit flesh were constantly higher in Jonathan than in Fuji. Nitrogen and phospharus contents were considerably higher in Jonathan during June to September. However, the contents of potassium, calcium, and magnesium in the fruit skin were higher in the early season for Jonathan but ended up lower in late season for Jonathan.
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