First Report of Shot-hole on Flowering Cherry Caused by Burkholderia contaminans and Pseudomonas syringae pv. syringae.

Abstract

The shot-hole disease (SH) is one of the most common and important diseases affecting the flowering cherry (FC; Prunus × yedoensis Matsumura; Somei-yoshino ) trees in South Korea every year, resulting in premature defoliation and reduced flowering in the following year. However, pathogens associated with the disease remain unknown, which has rendered disease management challenging. Here, the pathogens associated with SH, their biochemical characteristics, and their host range were elucidated. Detached leaf and in planta assays revealed that two biofilm-forming bacteria, namely Burkholderia contaminans (Bc) and Pseudomonas syringae pv. syringae (Pss), caused SH of FC trees. These pathogens were recorded for the first time as the causes of SH of FC trees in South Korea. Additionally, the two pathogens induced similar disease symptoms in several stone fruits belonging to the genus Prunus, including peach (P. persica), plum (P. salicina), and apricot (P. mume), with peach being the most susceptible. These results indicate that Bc and Pss caused SH on FC trees and presented a broad spectrum of hosts. Furthermore, Xanthomonas arboricola pv. pruni, the causative agent of leaf spot on stone fruits, incited brown spots and shot holes on FC leaves. Therefore, FC trees are susceptible to infections by various pathogenic bacteria, including Bc, Pss, and Xap. These findings will be of great importance as a reference for effective management of SH in the face of possible cross-infection between Prunus species in the future.