Abstract
Since 2004, oak wilt disease has occurred in northern Nagano Prefecture, in central Japan. Similar damage occurred in the same area in 1750. According to old documents, many oak (Quercus spp.) trees in the Shinto shrine forest began to discolor in the summer, and withered and died that autumn. There was no treatment for the outbreak, which was related to an insect infestation of the trunks. The next year, 35 damaged oak boles (19∼35 cm in diameter) were sold, and the resulting funds were used to repair the shrine buildings. Many of the other boles were used to produce 500 bales (about 9.4 t) of charcoal. These findings suggest that the disease in 1750 was oak wilt disease caused by the fungus Raffaelea quercivora, carried by the oak borer Platypus quercivorus. In other words, P. quercivorus has long inhabited Japan and oak wilt disease has recurred occasionally since the Edo era in local areas with many large trees, like shrine forests.
