horse chestnut

My chestnut tree, approx 115 years old, has the phytosporum (spelling?) disease I think. Several spots with blackened leakages from the splitting bark. Very visible now on the bare trunk. Last year it looked healthy and this year too the buds and candles look ok. It is in a windy spot and shaped by the prevailing wind, but healthy even if the branches are weeping (almost as a willow; by the way so is the lime, presumably due to the wind?)/ I'll leave it of course - hoping I'm mistaken - but what are the signs of irreversible decline? It is in a separate corner so no danger to humans of falling branches etc. Can it infect other trees?

 

Hi Tor

It sounds as if your horse chestnut is suffering from bleeding canker, which is caused by the bacterium Pseudomonas syringae pv. aesculi. (BTW, up until recently it was thought that bleeding canker was caused by Phytophthora [not phytosporum], but this is now no longer the case.)

Bleeding canker can often be fatal, although there have been instances where infected trees have continued to live with the infection, sometimes sealing over the wounds and carrying on normally. Your tree's reaction to this disease will depend on the its vigour as well as that of the bacteria. Sadly there is no control available for this disease - it will be a battle of wills between your tree and the infection.

Irreversible decline would be indicated by the stem being girdled completely by the weeping lesions. This would put the tree at a greater chance of failure. Large limbs with excessive girdling/cankers would also be susceptible to breakage. Horse chestnut is a brittle tree at the best of times, without further weakening caused by this disease.

The infection can spread to other horse chestnuts, but it is not clearly understood how (most probably wind or water bourne).

 

Thanks! So far it is just in spots, 5-10, on the lower part of the trunk, and will of course wait and see.