Chaga mushroom (Inonotus obliquus), which has invaluable medicinal uses, grows only on
living trees. To date, it is still harvested from its natural habitat and is not cultivated artificially.
We artificially cultivated chaga mushrooms by inoculating its sawdust spawns on Betula
platyphylla var. japonica in 2007, and monitored mushroom growth on the inoculated trees for 9
years. The mushrooms grew less than 1 cm per year, with the largest mushroom growing up to 9
cm in the 9 years of study. There was no difference in the growth (diameter at breast height) of
trees with viable and non-viable I. obliquus. In conclusion, artificial cultivation of chaga
mushroom was successful. Our findings suggest that selection of large B. platyphylla var.
japonica as host tree could lead to better I. obliquus productivity. Further improvements of the
method are needed to increase the success rate of I. obliquus inoculation.