02518nas a2200229 4500008004100000022001400041245010700055210006900162260003800231300001400269490000700283520178600290653002302076653002402099653002102123653002702144100001802171700001502189700001402204700001502218856005502233 2011 eng d a1365-305900aInfectivity and sporulation potential of Phytophthora kernoviae to select North American native plants0 aInfectivity and sporulation potential of Phytophthora kernoviae  bBlackwell Publishing Ltdc04/2012 a224–2330 v613 a

Phytophthora kernoviae exhibits comparable epidemiology to Phytophthora ramorum in invaded UK woodlands. Because both pathogens have an overlapping geographic range in the UK and often concurrently invade the same site, it is speculated that P. kernoviae may also invade North American (NA) forests threatened by P. ramorum, the cause of Sudden Oak Death. This paper addresses the susceptibility of select NA plants to P. kernoviae, including measures of disease incidence and severity on wounded and unwounded foliage. The potential for pathogen transmission and survival was investigated by assessing sporangia and oospore production in infected tissues. Detached leaves of Rhododendron macrophyllum, Rhododendron occidentale and Umbellularia californica, and excised roots of U. californica and R. occidentale were inoculated with P. kernoviae and percent lesion area was determined after 6 days. Leaves were then surface sterilized and misted to stimulate sporulation and after 24 h sporangia production was assessed. The incidence of symptomless infections and sporulation were recorded. All NA native plants tested were susceptible to P. kernoviae and supported sporangia production; roots of U. californica and R. occidentale were both susceptible to P. kernoviae and supported sporangia production. Oospore production was also observed in U. californica roots. The results highlight the vulnerability of select NA native plants to infection by P. kernoviae, suggest that symptomless infections may thwart pathogen detection, and underscore the importance of implementing a proactive and adaptive biosecurity plan.

10aforest biosecurity10ahost susceptibility10ainvasive disease10aPhytophthora kernoviae1 aFichtner, E J1 aRizzo, D M1 aKirk, S A1 aWebber, JF uhttp://dx.doi.org/10.1111/j.1365-3059.2011.02506.x