Today, the Horse Chestnut is under attack from a bacterium called Bleeding Canker, a disease that appears as black tarry deposits on the tree trunk and branches that oozes out of the wood

Plant Pathologists working for the tree and shrub care provider Bartlett Tree Experts and Reading University are relentlessly on the heels of this diseases in an attempt to establish a successful cultural and biological treatment programme to Save the Horse Chestnut from this widespread and increasing problem.  Here are some highlights of what has been learned.

Bleeding Canker is a bacterial disease and Chestnuts have long been known to suffer from a cankerous infection caused by the fungal-like Phytophthora.  Around five years ago, however, a steep increase in the number of reports of bleeding canker prompted researchers to review earlier analysis.  It was then that they realised a new bacterium identified as Pseudomonas syringae pv aesculi  had taken hold.

While it is still unclear how the disease spreads, it is thought that the vectors of this disease may be insect activity which can spread the bacterium from tree to tree. Once the bacterium enters a tree, its effects can be catastrophic. The Bacterium attacks and kills the bark, creating a wound. The tissue then becomes discoloured and extends, oozing a sticky tar substance that eventually takes on a hardened black varnish appearance.

Research in Australia and California suggests that the application of a Phosphite based materials to the bark, stem and soil will strengthen the plants defense system and dry up the bleeding canker and arrest the advance of the disease. Phosphite treatments also reduce levels of new infestation. The results achieved by Bartlett Tree Experts have been very encouraging. The recovery of infected trees caught early in the disease cycle has exceeded all expectations. Thus, a simple procedure provides great results in preserving cherished trees.

While other diseases affect the Horse Chestnut, this threat have the most potential to cause serious damage. It is important that the Horse Chestnut is not lost in the same way as the venerable Elm and that part of our landscape tradition is kept intact for future generations to enjoy