So, if clearing leaf litter is worth it, then what should be done about it?
Firstly, it is worth noting that general leaf litter is a fantastic ecological product that allows the recycling of nutrients and provides shelter and food sources for a wide range of animals, plants, fungi and all other sorts of microscopic creatures.
But, the horse-chestnut leaf-miner overwinters in the leaf litter and emerges in the spring to attack the leaves of horse chestnut trees.
Nigel Straw and colleagues at Forest Research produced a report showing that to effectively kill the moth pupae it is neccesary either to:
- Cover the leaves in a layer of soil to stop the adult moths emerging. To quote from the Forest Research website, you will need to "cover the leaves with a 10cm layer of soil or 15-30cm layer of other plant material, and leave the heaps undisturbed until the end of May".
- Compost the leaves at a high temperature. (The easiest way is via a commercial composting scheme, e.g. through your local council.)
* Why do we say 'appeared to be' and not 'is'? Well, the answer is because the formal statistical analysis of this is still on-going. We'll have the answer soon.