Conkers in Decline

Who doesn't have fond youthful memories of conkers hanging from shoe laces smashed against an opponent's until one breaks. Even though our neighbourhood has lots of trees the Horse Chestnut is quite rare in Johnstown. Originating from the Balkans 'Aesculus hippocastanum' has long been naturalised in Ireland so it will come as a shock to discover that these trees could be wiped out within a generation.

Disease

The forest service of the Department of Agriculture says that 'Bleeding Canker' is is increasingly common in Ireland killing horse chestnuts in significant numbers. Having wiped out 50,000 trees in the UK (stated in 2016) the bacteria Pseudomonas syringae pv aesculi is widespread and attacks the tree bark causing it to bleed a dark sticky fluid. Sweeping silently through Europe since the early 2000's Phoenix Park identified one of their first cases of the disease in 2010.

To a slightly lesser extent Leaf Blotch is also common and causes browning of the leaves, especially during years with wet springs, which stunts growth particularly in young trees.

Pests

The leaf miner moth is an invasive species whose caterpillars feed inside leaves causing brown or white blotch mines to develop between the leaf veins causing the tree to drop its leaves much earlier and conker sizes are reduced. It's environmentally undesirable and impractical to spray pesticide on a large tree and there's no suitable pesticide treatments available for home gardeners.

To a lesser extent the horse chestnut scale is an annual pest which a has been attacking horse chestnuts since the 60's.