Pests and Diseases Viewer

Horse Chestnut Bleeding Canker


Horse Chestnut Bleeding Canker

Usually appear in

All Year

Back to Pests and Diseases

Caused By:-     The Bacteria Pseudomonas syringae pv. aesculi


Horse Chestnut Bleeding Canker is a disease of the bark of horse chestnut which is caused by the bacterium Pseudomonas syringae pathovarv aesculi. It causes cankers which bleed a dark or reddish brown sticky fluid that ooze from cracks in the bark where the infections occur.. It is specific to horse chestnuts and both the white flowered Aesculus hippocastaneum and the red A. x carnea are affected. Until recently 2008 it was thought to be caused by the fungus-like micro-organism Phytophthora, which causes the affected bark to bleed a dark sticky fluid, but this was a rare occurance. This latest spread of infections is spreading fast and the cause has now been identified as P. syringae pv. aesculi. Cutting away the outer bark over infected areas will reveal a brown or purple discoloured area of inner bark. Healthy inner bark is a white or pinkish colour. The bleeding fluid is produced by the tree in response to the infection, which kills the inner bark, cambium and outer layers of wood, causing disruption to water and nutrient transport. If the canker girdles the stem, the stem dies.
Trees of all ages have been affected by the recent disease upsurge. Young trees with a stem diameter of only 10cm (4 inches) are more likely to be killed as the smaller diameter of their trunks means that they can be girdled more quickly. However, the impact on the environment can be particularly profound when large, mature trees are infected and disfigured by the disease.
Cankers can be seen at any time of year. The effect on the tree is variable. Some infections last for years, being more or less stable with little effect on the tree. Others spread rapidly and cause die-back and even death of part or all of the tree. Picture by Joseph O'Brien, USDA Forest Service,
See these other Cankers Apple and Pear, Bacterial, Bleeding, Canker, Cytospora, European, Mulberry, Parsnip, Pear and Apple, Phomopsis, Poplar Bacterial, Rose Stem and Dieback, Willow Black.


It is believe that this disease has been imported from India where it was known. Wound damage may be the reason why this disease gets a hold. If the disease is on a branch it may be possible to prune the branch out and burn the affected wood. Some infections stabilise, so it is not necessary to remove the tree unless they are in a dangerous condition, but keep affected trees under observation and call in an aborist to examine the tree. If you have to cut, immediately paint the wound with a pruning sealant and the tools must be disinfected in between pruning. Use 9 parts methylated spirits to 1 part disinfectant cleaning agent, such as Jeyes Fluid.

Back to top