<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Pérez-Sierra, A.</style></author><author><style face="normal" font="default" size="100%">Kalantarzadeh, M.</style></author><author><style face="normal" font="default" size="100%">Sancisi-Frey, S.</style></author><author><style face="normal" font="default" size="100%">Brasier, C.M.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Phytophthora siskiyouensis causing stem lesions and cankers on Alnus incana</style></title><secondary-title><style face="normal" font="default" size="100%">New Disease Reports</style></secondary-title><short-title><style face="normal" font="default" size="100%">New Dis. Rep.</style></short-title></titles><dates><year><style  face="normal" font="default" size="100%">2015</style></year><pub-dates><date><style  face="normal" font="default" size="100%">Jun-06-2017</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://www.ndrs.org.uk/contents.php?vol=31http://www.ndrs.org.uk/article.php?id=031017</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">31</style></volume><pages><style face="normal" font="default" size="100%">17</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;div id=&quot;repbody&quot; class=&quot;clearfix&quot;&gt;&lt;p&gt;In late summer 2013, stem cankers and sparse foliage were reported on European grey alder (&lt;em&gt;Alnus incana&lt;/em&gt;) growing on a 500 ha site recently-planted with broadleaf and coniferous trees in south-west England. A site visit showed that approximately 10% of&amp;nbsp; more than 1000 grey alders (thought to have been imported from Europe and planted in the late 1990s) had symptoms including bleeding stem lesions similar to those caused by &lt;em&gt;Phytophthora alni &lt;/em&gt;(Gibbs &lt;em&gt;et al.&lt;/em&gt;, 2003). In November 2013, samples were collected from stem lesions (Fig. 1), roots (internal lesions tracking-down from stem lesions) and rhizosphere soil from symptom-bearing trees. Tissue from root and stem lesion margins was plated onto &lt;em&gt;Phytophthora &lt;/em&gt;selective medium (SMA) (amended as per Brasier &lt;em&gt;et al.&lt;/em&gt;, 2005) and incubated at 20°C for 48 hrs. Green apples were used as baits for soil samples by inserting a few grams of soil under a flap cut in the side of the apple and incubating for 4-7 days at 20°C. Isolation from developing SMA mycelial cultures and incubated apple baits onto potato dextrose agar (PDA) and carrot agar (CA) was then undertaken.&lt;/p&gt;&lt;p&gt;After 14 days on PDA at 20°C in the dark, colonies exhibited a distinctive stellate growth pattern (Fig. 2a). On CA they had a diffuse 'frosty' appearance (Fig. 2b). On CA, oogonia with predominantly paragynous antheridia and aplerotic oospores were abundant. Partially-caducous sporangia formed when plugs from colonies on CA were submerged in unsterile pond water held at 20°C in the dark. Sporangia (46-51 μm wide) were semi-papillate and were ovoid, reniform, elongated or irregular in shape (Fig. 3). Sporangial morphology and dimensions corresponded to &lt;em&gt;Phytophthora siskiyouensis&lt;/em&gt; (Reeser &lt;em&gt;et al&lt;/em&gt;., 2007) and sequences of ITS and &lt;em&gt;cox&lt;/em&gt;II regions supported this identification (GenBank Accession Nos. KP207601 and KP207602).&amp;nbsp;&lt;/p&gt;&lt;p&gt;One isolate of &lt;em&gt;P. siskiyouensis&lt;/em&gt; was obtained from each of three different symptomatic trees; one from a root lesion, one from a stem lesion and one from associated soil. Koch’s postulates were tested by inoculating two-year-old potted &lt;em&gt;A. incana&lt;/em&gt; saplings with the three isolates. A small wound was made on the stem 10 cm above soil level. A CA plug colonised by &lt;em&gt;P. siskiyouensis&lt;/em&gt; was inserted and the wound was sealed with Parafilm. Nine saplings were inoculated per isolate and maintained at 20°C with a 12-hr-photoperiod. Three control saplings were inoculated with sterile CA plugs. After 20 days, cankers and bleeding were visible externally on all of the trees inoculated with &lt;em&gt;P. siskiyouensis&lt;/em&gt; (Fig. 4). The bark was peeled away to reveal phloem lesions extending approximately 2-4 cm above and below the inoculation point. No lesions developed on control trees. After re-isolation onto SMA, a &lt;em&gt;Phytophthora &lt;/em&gt;sp. was recovered from all of the inoculated trees but not from the controls and it was identified as &lt;em&gt;P. siskiyouensis &lt;/em&gt;by morphology (Reeser &lt;em&gt;et al&lt;/em&gt;., 2007) and sequencing of the ITS region.&lt;/p&gt;&lt;p&gt;&lt;em&gt;Phytophthora siskiyouensis &lt;/em&gt;is a recently-described species in the USA, isolated from stem lesions on myrtlewood (&lt;em&gt;Umbellularia californica&lt;/em&gt;) and tanoak (&lt;em&gt;Lithocarpus densiflorus&lt;/em&gt;; synonym of&lt;em&gt; Nothocarpus densiflorus&lt;/em&gt;) and from soil and stream water, in south-west Oregon (Reeser &lt;em&gt;et al&lt;/em&gt;., 2007). It has also been reported causing stem lesions on Italian alder (&lt;em&gt;Alnus&lt;/em&gt; &lt;em&gt;cordata&lt;/em&gt;) in California (Rooney-Latham &lt;em&gt;et al&lt;/em&gt;., 2007). This is the first report of &lt;em&gt;P. siskiyouensis&lt;/em&gt; in the UK and, to our knowledge, in Europe, and the first report of &lt;em&gt;P. siskiyouensis&lt;/em&gt; causing stem cankers on &lt;em&gt;A. incana&lt;/em&gt;. Its occurrence within a recently-planted site suggests a possible origin on introduced nursery stock. &lt;em&gt;P. siskiyouensis&lt;/em&gt; has the potential to cause further damage to &lt;em&gt;Alnus&lt;/em&gt; spp. and other plant species in Europe. Its comparative pathogenicity on various alder species is under investigation.&lt;/p&gt;&lt;/div&gt;</style></abstract></record></records></xml>