BiodivERsA_RESIPATH: Responses of European Forests and Society to Invasive Pathogens

The survey for Phytophthora in Glomma (baiting) in 2014, when P. gonapodyides, P. lacustris and P. plurivora were detected, was followed up by symptom inspection on trees along the river in August and September 2015. In addition to tissue samples from symptomatic trees, soil samples were taken from the same locations. A total of 41 samples were brought back to the laboratory, hereof 23 soil samples. Most tissue samples were from grey alder (Alnus incana), but also birch (Betula pubescens) and Salix spp. The soil samples were mixed with water and baited with leaves from Rhododendron. In addition to collecting samples, a lateral flow devise/assay (LFD) was used in the field to detect Phytophthora (not species specific) from trees with bleeding cankers. The test was positive on grey alder in five locations between Skiptvet to north of Koppang. However, symptoms were observed north to Tynset on grey alder, but we were not able to isolate or get a positive LFD there. This was probably due to the age of the bleeding cankers, they were not fresh. We know from working with Phytophthora on beech, that it is very difficult to isolate the pathogen from older infections. Results from isolates collected in 2015, will be available by the end of February 2015.The last samples were collected along Glomma on 26-27 September 2016.

Invasive alien species pose a serious global threat to biodiversity by driving native species to extinction via competitive exclusion and by their ability to modify entire landscapes. The selected tree species are not only an integral part of their ecosys tems but are also economically important and supply crucial environmental services to European society, such as biodiversity, watershed protection, stabilisation of river banks, as well as recreational and cultural values. Due to different mortality patte rns, the array of host-pathogen combinations enables the study of differential effects on the host population in terms of demographics and evolution. The high ecological and economic impact caused by invasive pathogens nowadays necessitates the developmen t of an early detection system and to increase knowledge on the importance of different pathways for their introduction and spread. Ultimately, an efficient response from society to mitigate the impact of invasive pathogens also depends on the public perc eption and the communication between researchers and stakeholders in society. The contribution from Bioforsk is restricted to surveying of our largest river, Glomma, for Phytophthora spp. as part of WP4: "Detection and early warning of fungal and oomycete pathogens". This WP will provide a validated high through-put system for the early detection of potentially harmful and invasive fungal/oomycete taxa.