Question to the Department for Environment, Food and Rural Affairs:

To ask the Secretary of State for Environment, Food and Rural Affairs, what steps her Department is taking to assess the potential threat to chestnut trees from moth-borne diseases.

We are committed to doing all we can to prevent plant pests and diseases reaching our borders and to build the resilience of our trees and plants. From 2012 to 2019 we will have invested more than £37 million into tree health research, including studying the interactions between horse chestnut leaf miner and other pests.

Our approach, led by the Government Chief Plant Health Officer, involves the systematic, proactive screening of potential new and emerging risks, which are listed in the Plant Health Risk Register.

This includes pests and diseases which can affect horse chestnut trees, such as moths like the horse chestnut leaf miner. This is listed in the Risk Register with, after current mitigations, a relative risk rating of 24 (out of a possible 125). Horse chestnut leaf miner larvae can damage horse chestnut leaves on an annual basis, causing leaves to turn brown and fall earlier than usual. However, on its own the pest does not significantly impair trees' health and affected trees will usually grow normally the following spring. Removing fallen leaves during autumn and winter and composting or covering them can help reduce damage by destroying pupae and preventing adult moths emerging the next spring.