Abstract
The influence of calcium formate on flower thinning of ‘Fuji’ apple (Malus domestica Borkh.) was investigated. Spraying 1% calcium formate on the pistil 1 hour before, 1 or 24 hours after pollination reduced fruit set. Spraying 1% calcium formate on the pistil 24, 48 or 72 hours after pollination, fruit set was clearly reduced by spraying 24 hours after pollination, whereas spraying 72 hours after pollination was ineffective. When spraying calcium formate at concentrations ranging from 0.2 to 1.0%, higher concentrations of calcium formate were more effective for flower thinning. Spraying calcium formate ranging from 1.0 to 3.3% on flower bud, did not have any significant effect on fruit set. Neither one-time nor two-times of 1% calcium formate application was effective. Therefore, directly exposing the pistil to calcium formate seemed to prevent fertilization and reduce fruit set.
