SummaryAn analysis of incidence of Phytophthora spp. in 732 European nurseries producing forest transplants, larger specimen trees, landscape plants and ornamentals, plus 2525 areas in which trees and shrubs were planted, is presented based on work conducted by 38 research groups in 23 European countries between 1972 and 2013. Forty-nine Phytophthora taxa were recorded in 670 nurseries (91.5%); within these nurseries, 1614 of 1992 nursery stands (81.0%) were infested, although most affected plants appeared healthy. In forest and landscape plantings, 56 Phytophthora taxa were recovered from 1667 of 2525 tested sites (66.0%). Affected plants frequently showed symptoms such as crown thinning, chlorosis and dieback caused by extensive fine root losses and/or collar rot. Many well-known highly damaging host-Phytophthora combinations were frequently detected but 297 and 407 new Phytophthora-host associations were also observed in nurseries and plantings, respectively. On average, 1.3 Phytophthora species/taxa per infested nursery stand and planting site were isolated. At least 47 of the 68 Phytophthora species/taxa detected in nurseries and plantings were exotic species several of which are considered well established in both nurseries and plantings in Europe. Seven known Phytophthora species/taxa were found for the first For. Path. 46 (2016) 134-163 doi: 10.1111/efp.12239 © 2015 http://wileyonlinelibrary.com/ time in Europe, while 10 taxa had not been previously recorded from nurseries or plantings; in addition, 5 taxa were first detections on woody plant species. Seven Phytophthora taxa were previously unknown to science. The reasons for these failures of plant biosecurity in Europe, implications for forest and semi-natural ecosystems and possible ways to improve biosecurity are discussed.

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Speci_c primers and dual!labelled~uorogenic probes were designed for polymerase chain reaction "PCR#! based detection of both\ mycorrhizal and pathogen DNA[ Based on the on!line connection with an auto! mated ABI Prism 6699 sequence detector\ amplicon quanti_cation was directly performed during the PCR[ The starting copy numbers of target sequences present in each reaction were calculated by comparing the Ct!values of unknown samples to the Ct!values of standards with known amounts of DNA[ The Ct!value depends on the input of starting copies and is de_ned as that cycle num! ber at which a statistically signi_cant increase in the reporter~uorescence can _rst be detected[ DNA was extracted from 00 as well as 099 spores of the mycorrhizal fungus Glomus mosseae and quanti_ed by using the~u! orescent PCR technology[ Furthermore\ DNA of Phy! tophthora infestans\ causal agent of late blight of potatoes\ was quanti_ed after extraction from arti_cially infected potato tubers and naturally infected _eld plants[ Phytophthora citricola DNA\ causing root!rot diseases\ was quanti_ed after isolation from arti_cially inoculated seedling roots of beech and oak [ The results demonstrate that novel real!time PCR techniques are a powerful uni! versal tool in modern phytopathological research[ Zusammenfassung Real!time quantitative PCR] DNA!Bestimmung in isolierten Sporen des Mykorrhizapilzes Glomus mosseae und Nachweis von Phytophthora infestans sowie Phytophthora citricola in ihren Wirtsp~anzen Es wurden spezi_sche Primer und Fluoreszenzproben zum Nachweis von Mykorrhizapilz! sowie Pathogen! U[ S[ Copyright Clearance Center Code Statement] 9820Ð0674:88:3697Ð9398 , 03[99:9 DNA entwickelt[ Der Anstieg der im Verlauf der PCR gebildeten Produkte wurde wa Ãhrend der Reaktion unter Verwendung des ABI Prism 6699!Gera Ãtes direkt gemes! sen[ Die automatische Quanti_zierung der Amplicons fand anhand der Ct!Wertbestimmung statt\ wobei ein Vergleich mit den Ct!Werten von Standardproben bekannter DNA!Konzentration erfolgte[ Der Ct!Wert ist abha Ãngig von der DNA!Menge und repra Ãsentiert den Schritt im PCR!Zyklus\ bei dem erstmalig ein Fluoreszenz! signal gemessen werden kann[ DNA wurde aus 00 bzw[ 099 Sporen des Mykorrhizapilzes Glomus mosseae extrahiert und mit Hilfe der beschriebenen PCR!Technik quanti_ziert[ Daru à ber hinaus ist die Vermehrung von Phytophthora infestans!DNA\ dem Erreger der Kraut! und Knollenfa Ãule bei der Karto}el\ in ku à nstlich in_zier! ten Karto}elknollen sowie natu à rlich in_zierten Feldp~anzen bestimmt worden[ Au)erdem wurde die DNA des Wurzelfa Ãule!Erregers Phytophthora citricola in Wurzelproben von ku à nstlich in_zierten Keimlingen der Buche und Eiche quanti_ziert[ Die Ergebnisse zeigen\ da) sich die neuen~uoreszenzgestu à tzten Techniken zur direkten Quanti_zierung von PCR!Produkten universell und leistungsfa Ãhig in der modernen phytopathologischen Forschung einsetzen lassen[

Since its first isolation from Salix roots in 1972, isolates of a sexually sterile Phytophthora species have been obtained frequently from wet or riparian habitats worldwide and have also been isolated from roots of Alnus and Prunus spp. Although originally assigned to Phytophthora gonapodyides on morphological grounds, it was recognized that these isolates, informally named P. taxon Salixsoil, might represent a separate lineage within ITS Clade 6. Based on phylogenetic analyses and comparisons of morphology, growth-temperature relationships and pathogenicity, this taxon is formally described here as Phytophthora lacustris sp. nov. Isolates of P. lacustris form a clearly resolved cluster in both ITS and mitochondrial cox1 phylogenies, basal to most other Clade 6 taxa. Phytophthora lacustris shares several unusual behavioural properties with other aquatic Clade 6 species, such as sexual sterility and tolerance of high temperatures, that have been suggested as adaptations to riparian conditions. It appears to be widespread in Europe and has also been detected in Australia, New Zealand and the USA. It was shown to be weakly or moderately aggressive on inoculation to Alnus, Prunus and Salix. The extent of P. lacustris' activity as a saprotroph in plant debris in water and as an opportunistic pathogen in riparian habitats needs further investigation. Its pathogenic potential to cultivated fruit trees also deserves attention because P. lacustris has apparently been introduced into the nursery trade.

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