Abstract
Control of bacterial blossom blight of kiwifruit by treatment of ringing to main trunk were examined. Ringing treatment more than 5mm in width at approximately 25 days before flowering showed a stable effect on the control of the disease. Changes in percentage of water content, shoot length and percentage of flower buds with morning dew were examined by ringing treatment on the main trunks to reveal the mechanism of disease suppression by the treatment. Ringing treatment showed a marked effect on the suppression of bacterial blossom blight caused by Pseudomonas syringae, a causal pathogen of the disease, although no difference was observed in the infection rate. Water content of trees showed no significant effect by the ringing treatment. Ringing treatment effectively suppressed the shoot elongation, and formation of morning dew on the flower buds in comparison with that of the control. However, P. syringae could be detected within the morning dew. Since decrease in the formation of morning dew correlates positively with decrease in shoot length. These results suggested that the reduction in the disease occurrence by ringing treatment partly resulted from the decrease in the amount of morning dew on flower buds.
