Bacterial canker of plum caused by Pseudomonas syringae pathovars, as a serious threat for plum production in the Netherlands

In the Netherlands, bacterial canker of plum trees (Prunus domestica) caused by Pseudomonas syringae pathovars syringae and morsprunorum is a recent and serious problem. The trunks of the affected plum trees are girdled by cankers resulting in relatively sudden death of the trees 1 to 4 years after planting. Disease incidence can be very high, and sometimes complete orchards have to be removed. Recently, plum cultivation in the Netherlands has changed from a relatively extensive into an intensive cultivation. However, due to the risks of losses of trees due to bacterial canker, growers are reluctant to plant new orchards. In general, nurseries and fruit growers are not familiar with bacterial diseases and lack knowledge to prevent infections. Therefore, control strategies to manage plum decline have to be developed.