Written question asked by Sandra Gidley (Liberal Democrat) on Thursday, 11 October 2007, in the House of Commons. It was due for an answer on Monday, 15 October 2007. It was answered by Joan Ruddock (Labour) on Monday, 22 October 2007 on behalf of the Department for Environment, Food and Rural Affairs.

Trees: Diseases

Question: To ask the Secretary of State for Environment, Food and Rural Affairs if he will make a statement on the spread of Cameraria ohridella.

Answer: Horse chestnut leaf miner (Cameraria ohridella) was first discovered in Wimbledon in 2002 and has since continued to spread northwards, into south Yorkshire and Cheshire, eastwards almost throughout East Anglia, and it has reached the border counties of Wales.We are continuing to monitor its movement, and invite the public to report any sightings to us to help us do this. Sightings can be reported to the entomology branch of Forest Research on 01420 22255.The larvae of Cameraria ohridella devour the leaves, but do not kill the trees, nor do they appear to have any long-term effect on tree health or vitality. Although trees appear unsightly during infestation, they will leaf-out and flower normally in the following year.There are no effective control mechanisms available, especially where the trees occur together in large numbers, such as in parks and woodland. Research into control continues and gardeners can help to protect their horse chestnut trees by sweeping up and disposing of autumn leaves, which destroys the over-wintering pupae.

Secondary information