LAUSR

Simple Summary The impact on tree health from insect pests and microbial diseases that have moved across country borders has been increasing in recent years. This poses a significant challenge to government authorities, and a number of countries have been examining how effective volunteers from the general public can be in supporting tree health surveillance. Our paper describes a project led by the Open Air Laboratories (OPAL) in the United Kingdom which tested the extent to which the public were motivated to participate in tree health surveillance. It also examined whether ‘citizen scientists’ could provide information which would be of genuine use to officials and scientists responsible for national tree health. The results suggest that there was considerable engagement from the public, who completed over 2800 surveys covering more than 4500 trees. Nevertheless, despite designing the OPAL survey specifically for untrained individuals, the results were only partially of value to tree health specialists. The paper discusses the results and concludes that involving citizens with some existing expert knowledge is probably the most effective way to generate more reliable data. Lay citizens can contribute effectively at critical times when additional surveillance capacity is needed, provided that suitable guidance and support are given. Abstract The incidence of tree disease has been increasing in the UK in recent years as a result of a range of alien tree pests and pathogens new to the country. In the early 2010s government staff resources to monitor, identify and eradicate these pathogens were limited, so we tested the efficacy of “citizen scientists” to support these needs. The Open Air Laboratories (OPAL) is a successful citizen science programme launched in 2007, which at that time of launch involved over 650 thousand people in a range of environmental surveys. In 2012–2013, the Food and Environment Research Agency (Fera) and Forest Research staff worked with OPAL and its partners to launch a citizen science tree health survey in Great Britain and this was extended to cover Northern Ireland until it closed in 2019. Over 2800 surveys were completed including records on more than 4500 trees, the majority from urban areas. This paper discusses the results of the survey and their value for the assessment of tree health. It also considers the implications of engagement with the general public for the future of tree health surveillance. Recommendations are made for further development of the OPAL “model” and more generally for the role of citizen science in this important area.