It is essential that pests and diseases are identified correctly before they can be controlled efficiently and their spread prevented. In this presentation Dr Ana Perez-Sierra, Head of Tree Health Diagnostic and Advisory Service will describe the processes of diagnosis and some of the new technologies involved. We are currently facing a large number of new pest and disease threats arriving from overseas. Xylella fastidiosa is a bacterial pathogen with a large host range that is causing widespread damage in Europe. We all need to be aware of this pathogen and how to protect against it. The presentation was followed by a live Q&A session with Tom Jenkins - Head of Forest Research Wales for Conference delegates to put their questions to these tree health and diagnostic experts.