In the course of making the three necessary elments (N, P₂ O₅ and K₂O) tests of manures for the 2-year-old seedlings of Larix Kaempheri in the nurseries, we have observed that there may be some relations between the sort of manures and the severity of the damage of the root rot caused by Fusarium sp. and Rhizoctionia sp. In our poor nursery-beds, volcanic ash soil, the following results were obtained by the Latin square method: By giving phosphoric fertilizer the damage of the root rot is remarkably reduced, and the same tendency is observed in the case of potash manure, while, on the contrary, the severe damage is induced by the excessive amounts of nitrogenous manures.