Verticillium wilt is of increasing significance in European agriculture, especially in tree hosts such as olive and stone fruits, and in shade tree nurseries. In the period 1997–1998 eight European research groups participated in an EU-funded Concerted Action on this disease. Main results were the publication of “A Compendium on Verticillium wilts in tree species” (HIEMSTRA & HARRIS 1998) and an RTD-proposal submitted for financing to the 5th EU Framework Programme. This proposal was approved by the European Commission and the research started in March 2000. Ten research groups participate in a project that aims to provide essential elements for an efficient and environmentally sound management of Verticillium wilt in trees. The research concentrates on tree key areas: (1) pathogen variability, (2) host resistance, and (3) detection and risk assessment. In addition the project aims at harmonising methods, exchange of experience and continuation of the successful co-operation developed during the previous Concerted Action. The specific achievements of the project include information on genetic variation within the pathogen and on distribution and virulence of its subspecific groups; standardised methods to select for host resistance; resistant selections of olive and maple; molecular methods to detect the pathogen in soil and plants; and improved risk assessment procedures. Details on aims, methods and participating groups will be presented.