Infection tests of horse chestnut trees with <em>Pseudomonas syringae</em> pv. <em>aesculi</em>

Abstract

Trees of about 5 years age of Aesculus hippocastanum L. were planted and infected with Pseudomonas syringae pv. aesculi, the causal agent of the Pseudomonas bark disease of horse chestnut trees. To get knowledge on the infection ways of the pathovar, trees were treated by complete spraying or by watering the root area with bacterial suspensions. In other trees bacteria from agar plate cultures were spread on the bark or the bacteria were brought in the wood through artificial bark wounds. One tree showed already after 3 months the typical dark bark leakages, confirming Koch´s postulates. The other trees sampled after 3 years revealed that the pathovar could be re-isolated only from wound-infected trees and from two weakened or dead trees. Many of the wounds had been compartimentalized and/or totally over-walled, without a re-isolation of the bacterium. An infection via the leaves, the undamaged bark or the roots was not observed. It is assumed that P. syringae pv. aesculi infects A. hippocastanum through wounds.

DOI: 10.5073/JfK.2014.04.02, https://doi.org/10.5073/JfK.2014.04.02