Pest categorisation of Guignardia laricina

Abstract

Following a request from the European Commission, the EFSA Panel on Plant Health performed a pest categorisation of Guignardia laricina , a well-de fi ned and distinguishable fungal species of the family Phyllostictaceae. The pathogen is regulated in Council Directive 2000/29/EC (Annex IAI) as a harmful organism whose introduction into the EU is banned. G. laricina is native to East Asia and causes a shoot blight disease of Larix spp. Major hosts of G. laricina are European larch ( Larix decidua ) and two North American larch species ( Larix laricina (tamarack) and Larix occidentalis (Western larch)). Larix kaempferi (Japanese larch) is reported as susceptible. The only other host in nature is Douglas fi r ( Pseudotsuga menziesii) , which is reported as an incidental host, but various other conifers have been reported as susceptible following arti fi cial inoculation, including Picea abies . The fungus is not known to occur in the EU but could enter via plants for planting (including arti fi cially dwarfed plants) and cut branches of Larix spp. It could establish in the EU, as hosts are present and climatic conditions are favourable. The pathogen would be able to spread following establishment by natural dissemination of ascospores and pycnospores and by human movement of infected plants for planting. Should the pathogen be introduced in the EU, impacts can be expected in larch forests, plantations and nurseries, leading to reduced tree growth and ecosystem service provision. The key uncertainties concern the current distribution and level of impacts in the native range of the pathogen. The criteria assessed by the Panel for consideration as a potential quarantine pest are met. As the pest is not present in the EU, not all criteria for consideration as a regulated non-quarantine pest are met.