A novel means for accelerating the flowering time in Rosaceae fruit treessuch as apples and pears is provided, by inoculating a viral RNA into acotyledonof a Rosaceae fruit tree seedling immediately after rooting with a particleguntechnique, wherein the viral RNA is concentrated from a proliferating hostinfectedwith a recombinant apple latent spherical virus (FT-ALSV) expressing anArabidopsis FT gene.