We have a row of different sized Horse Chestnuts, I'd have thought a couple dating back to when the house was tarted up in the 1840s. Everyone forgets they were introductions, albeit 500 years ago, so celebrated are they in folklore and so resonant in memory. Although as non-natives they have limited ecological value (other than acting as giant feeding stations for pollinators in the spring), ours are very fine trees and, aesthetically, one of the best things we have. They feel very much part of our lives. The bees frolic in the blossom in spring, the sheep shelter under their vast spreading boughs in summer and in the autumn our youngest and his friends collect their conkers. Unfortunately they seem doomed, like many Horse Chestnuts in Britain.
In the south many trees now suffer from Chestnut Leaf Miner Moth infestation. The moth's mines make the leaves shrivel, brown and fall at this time of year, when the damage is most obvious. The moth seems to be a new species, originating in Greece, and has caused enormous damage to Horse Chestnuts throughout Europe.
Our trees, however, have a problem that's not largely disfiguring but rather more serious - bleeding canker. This used to be caused by a fungal pathogen, Phytophthora, which was regarded as being unusual. However, I gather the recent disease is related to a bacterium and is much more widespread. Although it is capable of killing a tree on its own it is as likely to weaken it for another disease to deliver the coup de grace. Unfortunately our Chestnuts are next to the orchard, and apple trees are apparently notorious in arbicultural circles for harbouring honey fungus; we've already lost two to it as a consequence.
As far as treatments go there have been some trials involving Allicin, an extract of garlic, but so far nothing conclusive. Why does there seem so little sense of crisis about a problem that could have a landscape scale impact? Whisper it not, but apparently old fashioned Bordeaux mixture seems to have worked on some trees in the past, which makes a lot of sense as I understand the disease is closely related to the bacterial canker you get on Cherries. Have any tests been done on it ? Not as far as I can see but, frankly, I'll give anything a go.
