What's eating my aesculus hippocastanum?

Horse chestnut is severely affected by horse chestnut leaf miner moth, which turns leaves brown by late summer across much of Europe. Bleeding canker (Pseudomonas) is a widespread disease threat. Deer browse young trees and grey squirrels strip bark. Leaf miner is now almost universal in the UK and Europe and is the dominant pest.

Brown blotch mines on leaves from midsummer; entire crown appears scorched by August, with premature leaf fall — a near-universal problem across Europe. Collect and bin or compost all fallen leaves to break the overwintering cycle; no effective chemical control on large trees; pheromone traps reduce adult populations marginally.

Bark stripped from young branches and trunks to reach the sweet sapwood; wounds expose timber to disease and can girdle limbs. Tree guards on young trunks; no practical control on established trees in urban settings.

Dense colonies on leaf undersides in spring; heavy honeydew drip onto surfaces below; sooty mold on affected leaves. Insecticidal soap or neem oil in spring; natural predators (ladybirds, parasitic wasps) usually suppress colonies by summer.

Young shoots and leaves browsed; bark rubbed by antlers in autumn, wounding the smooth bark of young stems. Spiral tree guards or wire mesh for trees in the first 3–5 years of establishment.