Abstract
To control of bacterial shot hole disease of peach, early elimination of twigs suspected to occur spring canker has been practiced. However, this method is not analyzed objectively. Thus, in order to index the decision factor for implementing this method, we investigated leaves and twigs around the early eliminated area (early eliminated plot) and around the areas where poorly growing twigs remained (no- eliminated plot) about characteristics of each twig (germination rate, average leaf length, twig length, twig discoloration, withering, and browning dent of leaf scar). Although the difference in diseased leaves ratio was not observed in both plots in 2017, it was tended to be low in the early eliminated plots in 2018 ; This result may suggest that the early elimination suppresses disease leaf development. Next, we have investigated the growing conditions of twigs that had practiced or not practiced the early elimination from 2016 to 2018 in field. As a result, the germination and development of leaves in the early eliminated twigs had poor. Moreover, from the logistic regression analysis, it was found that discoloration, withering of twigs and browning dent of leaf scar were important factor to decide the early elimination.
