Material World - 23/10/2008

Quentin Cooper examines how the UK's horse chestnut trees are under threat from invasive caterpillars spreading rapidly across Europe. Experts are concerned about the number of alien pests and diseases that are appearing in the UK, threatening the plants in our gardens, parks and across the countryside, as a result of being inadvertently imported into the UK. Quentin discusses these problems with Glynn Percival, plant physiologist at Bartlett Tree Research Laboratory, and Joan Webber, principal pathologist at the Forestry Commission, Farnham.