Table 1 Three important evolutionary concepts that have gained increased supporting evidence and have direct policy and practical implications and open directions for future research. A few key references are given; more are included throughout the main text

• Data on the biogeography of fungi and Phytophthora spp (Taylor et al. 2006)

• Emerging diseases in naive tree populations susceptible to new pathogens (Santini et al 2013)

• Emergence of aggressive pathogen species by hybridization of allopatric species with low interfertility barriers (Brasier 2001)

• “Lucky monoculture plantations” of exotic tree species that benefit from enemy escape (Pautasso et al. 2005)

• Appropriate trade regulations to decrease the risks associated with exotic pathogens (pathway approach) (Goss et al. 2009; Liebhold et al. 2012; Roy et al. 2014):

– traceability (passports) for plants-for-planting (Parke and Grünwald 2012)

– inclusion of the phylogenetic signal (Gilbert et al. 2012) and network theory applied to trade exchanges (Dehnen-Schmutz et al. 2010) in phytosanitary risk analysis

• Improvement of phytosanitary inspections (Liebhold et al. 2012; Eschen et al. 2015;

• Monitoring and surveillance

– improved and non-specific detection: generic detection (e.g. of Phytophthoras) and detection without a priori identification (Fears et al. 2014); sentinel trees in areas of origin of imported plants and use of arboreta

– improvement of disease management in nurseries (Parke et al. 2014)

• Further investigations of fungal diversity, especially in poorly studied and taxonomically rich ecosystems (Tedersoo et al. 2014)

• Theoretical developments for general predictions about the intensity of infection in various host-pathogen interactions; in-depth analyses of some communities, including life-history traits of host and pathogens, and genomic analyses of resistance genes in order to test predictions (Garcia-Guzman and Heil 2014; Gilbert and Webb 2007, Gilbert et al. 2012)

• Diversification, specialization and speciation in fungi and Phytophthora spp.: theoretical models and empirical approaches (Hamelin et al. 2011; Giraud et al. 2010)

• Adaptation of pathogens after introduction (Gladieux et al. 2015)

• Breakdown of resistance developed in breeding programs and deployed on large scales (McDonald and Linde 2002)

• Avoid multiple introductions: regulations aimed not only at the species but also intra-specific level, to avoid admixture and increase efficiency of biological control

• Evolutionary breeding and forestry (Lefevre et al 2014; Cavers and Cottrell 2015)

– use natural disease regulation mechanisms associated with tree diversity (Pautasso et al. 2005)

- consideration of defense trade-offs in tree breeding (Vogan and Schoettle 2015; Franklin et al. 2014)

- combination of resistance and tolerance mechanisms

- study and prediction of associational traits: target an "ideapop" or "ideacomm" instead of an ideotype (Anche et al. 2014)

• Evolutionary potential of pathogens

– experimental approach to the relative contributions of preadaptation and adaptation processes in invasive pathogens (Dlugosch and Parker 2008)

– species barrier effect: genes explaining the determinants of host range in fungal species and their potential for evolution (Schulze-Lefert and Panstruga 2011)

– trade-offs between virulence and other adaptive traits in pathogens: transmission, phenology (adaptation to climate) (Lively et al. 2014)

– effect of hybridization, admixture and multiple infections on the evolution of virulence (Susi et al. 2014)

– empirical studies of the impact of host tolerance and qualitative and quantitative resistance to disease on the evolution of virulence in forest systems

• Study of general/cross resistance mechanisms to disease in trees (Yanchuk and Allard 2009)

– nonhost resistance (Schulze-Lefert and Panstruga 2011), recessive resistance (van Schie and Takken 2014)

• Development of demo-genetic models of host–parasite interactions (e.g., Bazin et al. 2014)

• Ecological and evolutionary mechanisms regulating disease in wild plant pathosystems (Jousimo et al. 2014)

• Ecoimmunology (Schulenburg et al 2009)

• Tree pathogens have their own enemies

(Kiss 2003; Pearson et al 2009)

• Microbial communities around and inside trees are highly diverse (Buée et al. 2009; Peay et al. 2013)

• More systematic search of antagonists and hyperparasites in the native ranges of forest pathogens (Hale et al. 2014; Ridout and Newcombe 2015)

• Development of platforms for the coupling of metagenomic and phenotypic characterization of microbial communities (Lebeis 2014)

• Mycoparasitism by fungi, bacteria, virus

– significance in natural ecosystems (Tollenaere et al. 2014)

– role of hybridization, admixture and multiple infections on the efficiency and evolution of the biocontrol agents(Feau et al. 2014)

• Tree endophytic fungi: continuum or shift from opportunistic, weak pathogenicity, and their interaction with true pathogens (Pautasso et al. 2014).

• Mechanisms through which plants control their microbiota and through which the microbiome controls plant health (Berendsen et al. 2012; Pautasso et al. 2014).

– identifying the microbial species and community properties sustaining tree health (Hacquard and Schadt 2015)

– understanding the genetic vs. environmental determinism of beneficial microbiota (Lively et al. 2014; Pautasso et al. 2014); how does plant immune system regulate plant microbiote? (Lebeis 2014; Kliebenstein 2014)

– integration of the microbiota into epidemiological and evolutionary models of tree disease (Bálint et al. 2015)