Plant of the month : The Horse Chestnut
When I look out of my kitchen window in the morning, the horse chestnut is the first plant I see. There is a huge, mature tree just across the drive from me. Now, in early May, its five-fingered leaves are hanging limp-wristed. In a few weeks, when the leaves have spread and stiffened, there will be flowers like ice-cream cones balanced amongst the outstretched hands. And in the autumn, of course, fist-fulls of conkers will rattle down on the roof of my neighbour’s car.
I live in an estate village. The park around the Hall and all the lanes in the vicinity are heavily planted with horse chestnuts. Some few hundred years ago it was the tree to have – majestic and slightly exotic. Not a native, it was introduced to Britain from Turkey in the 16th Century.
But now the horse chestnuts are in trouble. In June, the leaves of every single tree in the village will start to show a brown mottling which increases over the summer and results in an autumn which comes several weeks too early as the ruined foliage is shed.
The culprit is a leaf-miner that eats the leaves from the inside and pupates over winter in the leaf litter at the base of the tree. Though shocking, these infestations have not been found to significantly weaken the tree and those livid green leaves will still appear next season.
However, the horse chestnut is under more serious attack from a bacterial canker which causes weeping sores on the bark. If the canker encircles a bough it will die. If it encircles the trunk, then the whole tree’s fate is sealed. A significant proportion of British horse chestnuts are infected with bleeding canker, for which there is no cure.
Though individual trees can scar and heal in some instances, the horse chestnuts face an uncertain future in Britain. A combination of leaf-miner and canker may prove too much for them. Losses from streets and parkland will be replaced with other species and it has been several years since the nursery has sold Aesculus in either the white or red-flowered forms.
With their drooping boughs and crowns like cumulus clouds, the horse chestnuts are village characters. Without them, the character of my village will be forever changed.