01711nas a2200181 4500008004100000022001400041245014900055210006900204300001400273490000800287520103900295100002201334700002001356700001901376700001901395700001501414856010001429 2005 eng d a0953-756200aPhytophthora kernoviae sp. nov., an invasive pathogen causing bleeding stem lesions on forest trees and foliar necrosis of ornamentals in the UK0 aPhytophthora kernoviae sp nov an invasive pathogen causing bleed a853 - 8590 v1093 a

A new Phytophthora pathogen of trees and shrubs, previously informally designated Phytophthora taxon C, is formally named here as P. kernoviae. P. kernoviae was discovered in late 2003 during surveys of woodlands in Cornwall, south-west England, for the presence of another invasive pathogen, P. ramorum. P. kernoviae is self-fertile (homothallic), having plerotic oogonia, often with distinctly tapered stalks and amphigynous antheridia. It produces papillate sporangia, sometimes markedly asymmetric with medium length pedicels. Its optimum temperature for growth is ca 18 $ınfty$C and upper limit ca 26$ınfty$. Currently, P. kernoviae is especially noted for causing bleeding stem lesions on mature Fagus sylvatica and foliar and stem necrosis of Rhododendron ponticum. P. kernoviae is the latest of several invasive tree Phytophthoras recently identified in the UK. Its geographical origins and the possible plant health risk it poses are discussed.

1 aBrasier, Clive, M1 aBeales, Paul, A1 aKIRK, Susan, A1 aDenman, Sandra1 aRose, Joan uhttp://www.sciencedirect.com/science/article/B7XMR-4RS503Y-5/2/2264e8910ee36f4e72255d6160ebf9e401777nas a2200181 4500008004100000245012700041210006900168300001400237490000800251520117100259100002201430700001401452700001701466700002201483700001701505700002501522856004801547 2004 eng d00aPhytophthora alni sp. nov. and its variants: designation of emerging heteroploid hybrid pathogens spreading on Alnus trees0 aPhytophthora alni sp nov and its variants designation of emergin a1172-11840 v1083 a

In 1993 a destructive new Phytophthora pathogen of riparian Alnus trees was discovered in the UK and subsequently shown to be present in other parts of Europe. The new Phytophthora comprised a group of emergent heteroploid hybrids, probably between P. cambivora and a species related to P. fragariae. These included a common, near tetraploid standard hybrid, the presumptive allopolyploid; and four scarcer major variant types with chromosome numbers intermediate between diploid and tetraploid, named the Swedish, Dutch, German and UK variants. The standard hybrid type is formally designated here as Phytophthora alni subsp. alni. The Swedish variant is designated as P. alni subsp. uniformis; and the Dutch, German and UK variants collectively as P. alni subsp. multiformis. The properties of the Dutch, German and UK variants within subsp. multiformis are informally described. The problems of designating emergent species hybrids under the International Code of Botanical Nomenclature and the reasons for the taxonomic choices made are discussed.

1 aBrasier, Clive, M1 aKirk, S A1 aDelcan, Jose1 aCooke, David, E L1 aJung, Thomas1 aMan In’t Veld, W A uhttp://dx.doi.org/10.1017/S0953756204001005