01942nas a2200145   4500008004100000022001400041245016600055210006900221260001600290300002000306520136300326100001701689700002001706856007001726       2018                        eng d  a0031-949X00aDistinct Trophic Specializations Affect How Phytophthora ramorum and Clade 6 Phytophthora spp. Colonize and Persist on Umbellularia californica Leaves in Streams0 aDistinct Trophic Specializations Affect How Phytophthora ramorum  cJun-05-2018  aPHYTO-06-17-0193 a<p><em>Phytophthora</em> spp. are regularly recovered from streams but their ecology in aquatic environments is not well understood. <em>Phytophthora ramorum</em>, invasive in California forests, persists in streams at times when sporulation in the canopy is absent, suggesting that it reproduces in the water. Streams are also inhabited by resident, clade 6 <em>Phytophthora</em> spp., believed to be primarily saprotrophic. We conducted experiments to determine whether differences of trophic specialization exist between these two taxa, and investigated how this may affect their survival and competition on stream leaf litter. <em>P. ramorum</em> effectively colonized fresh (live) rhododendron leaves but not those killed by freezing or drying, whereas clade 6 species colonized all leaf types. However, both taxa were recovered from naturally occurring California bay leaf litter in streams. In stream experiments, <em>P. ramorum</em> colonized bay leaves rapidly at the onset; however, colonization was quickly succeeded by clade 6 species. Nevertheless, both taxa persisted in leaves over 16 weeks. Our results confirm that clade 6 <em>Phytophthora</em> spp. are competent saprotrophs and, though <em>P. ramorum</em> could not colonize dead tissue, early colonization of suitable litter allowed it to survive at a low level in decomposing leaves.</p>1 aAram, Kamyar1 aRizzo, David, M  uhttps://apsjournals.apsnet.org/doi/pdf/10.1094/PHYTO-06-17-0196-R