As autumn arrives in a flurry of falling leaves any local will know Wimbledon Common Southside’s stunning procession of horse chestnut trees is not to be missed. However this colourful spectacle is under threat as the trees are increasingly affected by horse chestnut leaf miner and horse chestnut bleeding canker.

The leaf miner moth, a pest which originated in Macedonia in northern Greece, was first discovered in England along the Southside of Wimbledon Common in July 2002 and since then has expanded to affect every single horse chestnut tree on the Common. The suggested method of burning all the fallen leaves to reduce the number of leaf miners has been deemed inappropriate and impractical over such a large space and can unfortunately not be implemented on the Common.

However while the leaf miner moth impacts the trees negatively visually, causing early browning of the leaves and in some instances stunted growth, it does not appear to cause long-term damage like bleeding canker. This pathogenic disease has spread across Great Britain since 2003 at a rapid speed and is currently believed to affect over half the horse chestnut trees in the UK in some way. Bleeding canker reduces water supply to the tree’s crown by spreading through the inner bark, causing the bark to peel, discolouration of leaves, premature defoliation and in worse cases death. Younger trees are worst affected on the Common due to their smaller diameter meaning the disease has less distance to spread across, but older trees have been found with symptoms too. Some of the trees in less prominent locations have had to be felled to contain the problem which Peter Haldane, Wimbledon Common’s wildlife officer has said ‘is considerable and something that we are regularly monitoring.’