Effects of Hydrogen Cyanamide Spraying on Blooming and Leafing of ‘Kawazu-zakura’ (Prunus lannesiana Wils.) Cherry Trees in Minamiizu Region

The effects of hydrogen cyanamide (H2CN2) on blooming and vegetative bud leafing of ‘Kawazu-zakura’ (Prunus lannesiana Wils.) cherry trees were investigated in the Minamiizu region. In experiment 1, dormant limbs were sprayed with 0.75 or 1.00% H2CN2 on Nov. 17 and Dec. 18, 2008. On the branches sprayed with H2CN2 on Nov. 17, blooming and leafing occurred over 2 weeks earlier than in the controls. In experiment 2, dormant limbs were sprayed with 0.75, 1.00, or 2.00% H2CN2 on Nov. 16, 2009. At the lower concentrations of 0.75 and 1.00%, the effects of H2CN2 to promote blooming and leafing increased with its concentrations. At the highest concentration, however, vegetative buds showed a failure rate of about 40%. In experiment 3, whole trees were sprayed overhead with 0.75% H2CN2 on Nov. 18, 2009. For trees sprayed with H2CN2, blooming and leafing occurred over 2 weeks earlier than in the controls. These results were similar to those obtained in the sprayed limbs. When ‘Kawazu-zakura’ trees were sprayed with H2CN2 in Nov., 0.75 or 1.00% H2CN2 induced blooming 2–3 weeks earlier compared with natural blooming. Thus, the blooming period of ‘Kawazu-zakura’ in the Minamiizu region can be extended by forcing with H2CN2 to 32–39 days, including its natural blooming duration (about 18 days).