You maybe aware that our conker trees (Aesculus hippocastanum and its varieties) are under threat. The horse chestnut leaf miner grub eats the tissue between the outer layers of the leaves, reducing their ability to breathe and ultimately causing them to fall off. At the same time Horse Chestnut Leaf Blotch – a fungal condition is having exactly the same effect.  If your chestnut is shedding its leaves now, you know why.