To adequately anticipate and respond to the detection of new plant viruses in the event of outbreaks and interceptions, it is necessary to have a better understanding of the current virus reservoir, the “baseline”: knowledge on the species present, their host plants, and geographical distribution. In the case of a new finding (e.g. a pest new to science, a new host or an area where the pest was previously not known to be present), the question often arises whether phytosanitary measures are necessary or not.
Through the project 2020-A-347 ‘Baseline study on virus reservoirs in native plant species and crops (Virus reservoirs)’, multiple novel and unexpected viruses have been detected in a range of hosts across several partner countries. From a plant health perspective this highlights the need for countries to have a comprehensive knowledge of what is present within their territory in both crops and from environmental sources. This underlines the need for a continual programme of baseline surveillance of both commodity crops and the wider environment, and sharing of knowledge between states to establish baselines of virus presence at a regional level. It is evident that execution of these baseline studies and sharing of the output in an international setting will in time improve the quality and impact of these data: e.g. when the same virus is detected in different crops and areas. The volume of data generated and the time consuming nature of processing such data and then contextualizing those findings highlights the challenges in establishing such baseline programmes. Within this Euphresco project, contributors have generated and shared new and existing data from surveys and diagnostics to determine which viruses are already present in a territory, in relevant crops or potential reservoir hosts and which viruses are coming into their territories.

Samples were taken from both economically important crop species as well as from ornamental and wild species that are present in agricultural areas and/or native to natural ecosystems. Due to the large amount of viruses detected and the time-consuming data-analyses involved, several partners are still analysing part of their data. The value of the data generated is and will be maximised by sharing these within various data sharing initiatives (e.g. broader community data sharing initiative & Euphresco data sharing initiative 2020-G-346 Euphresco Virology community network 1 and 2). As a result, all pieces of information about certain virus species that were present can be combined and lead to a more comprehensive insight into the geographical distribution and epidemiology of a certain virus.  A selection of these findings from these baselines have already been made available as publications in scientific journals and more will follow. These publications will contribute to and hopefully prompt other countries to start similar initiatives. The importance in publishing these findings is that these data can be used as input for pest categorizations or pest risk analyses and will help to anticipate outbreaks in new areas and reduce the impact on crops on the one hand and prevent unnecessary regulation on the other hand.