Ana Pérez-Sierra is the Head of the Tree Health Diagnostic and Advisory Service at Forest Research in England (UK), the research agency of the Forestry Commission, a world leader in applied forest science. Over the past 25 years, Ana has worked in plant pathology (agriculture, horticulture, and forestry) and has undertaken and led tree health research, with a focus on a wide range of quarantine and regulated pests and new emerging diseases of forests. Graduate in Agriculture at Universidad Politecnica de Valencia, PhD at Birkbeck, University of London, on systematics, diagnostics, and epidemiology of the fungal genus Armillaria. From 1995 to 2003, she worked at the pathology department at the Royal Horticulture Society, Wisley Gardens, Surrey (UK). From 2004 to 2013 she worked at the Spanish Reference Laboratory for the Identification of Plant Pathogenic Fungi under the authority of the Spanish Ministry of Agriculture, Food, and Rural Environment (Spain) and she joined Forest Research in 2013. She has initiated a range of innovative research and diagnostic methods, significantly enhancing the knowledge of plant pathology to support the development of tree health policy and practice. She is actively involved in the development of an early warning system for the detection of tree pests and diseases at a UK-wide scale and is working in several citizen science projects.