Restoration outplantings of nursery-origin Californian flora are heavily infested with Phytophthora

Transcription

1 Restoration outplantings of nursery-origin Californian flora are heavily infested with Phytophthora Tyler B Bourret, HK Mehl, DM Rizzo, TJ Swiecki, EA Bernhardt & JM Hillman 6 th SOD Symposium, June 23, 2016

2 Survey of potentially infested restoration sites Santa Clara Valley Water District (SCVWD) has routinely performed restoration with nursery-reared native Californian flora Phytophthora species had been previously isolated from SCVWD outplantings & associated nurseries by Phytosphere (TJ Swiecki & EA Bernhardt), including P. tentaculata #5 on APHIS list of species to keep out of US Broad survey of 31 sites by Rizzo lab (H. Mehl & T. Bourret) & Phytosphere Sep May 2016

3 31 restoration sites sampled Sample site San Jose

4 36 plant species 193 samples collected Preference for symptomatic plants, especially known P. tentaculata hosts ~1 L soil + roots

5 Methods - soil sample processing & ID Baited with green pears & Rhododendron leaves Strains determined to species using morphotyping & ITS sequences Pythium s.l. was included but not reported (Mostly Phytopythium & Pythium s.s.)

6 Plant species Common name # samples # positive samples % samples # Positive sites # Psp. Aesculus californica Buckeye Acer negundo Boxelder maple Alnus rhombifolia White Alder Artemisia californica California sagebrush Artemisia douglasiana Mugwort Aster chilensis Chilean aster Baccharis glutinosa Salt marsh baccharis Baccharis pilularis Coyote brush Baccharis salicifolia Mulefat Ceanothus thyrsiflorus Blue blossom Clematis ligusticifolia Virgin's bower Dead plant (unknown sp.) Empty planting site Diplacus aurantiacus Sticky monkey flower Euthamia occidentalis Goldenrod Frangula californica Coffeeberry Helenium bignonia Sneezeweed Heteromeles arbutifolia Toyon Juncus sp. Rush (unknown sp.) Lepechinia calycina Pitcher sage Platanus racemosa Sycamore Populus fremontii Fremont cottonwood Prunus ilicifolia Holly-leaf cherry Quercus agrifolia Coast live oak Quercus douglasiana Blue oak Quercus lobata Valley oak Quercus sp. Oak (unknown sp.) Quercus wislizenii Canyon live oak Rhamnus crocea Redberry buckthorn Rosa californica CA wild rose Rubus ursinus CA blackberry Salicornia pacifica Pickleweed Salix sp. Willow (unknown sp.) Sambucus mexicana Blue elderberry Sambucus racemosa Mexican elderberry Sambucus sp. Elderberry (unknown sp.) Symphoricarpos laevigatus Snowberry Umbellularia californica Bay laurel total samples 74 Phytophthorapositive 27 yielded more than one species 36 plant species (28 associated with positive samples) Phytophthora recovered

7 Plant species Common name # samples # positive samples # Psp. Phytophthora species list Artemisia douglasiana Mugwort CAS, CHL, CRA, CRY, HYD, INU, LAC, MUL, PAR, PIN, POLxMAR, ROS, MUG, OAK, THE, THExAMN Juncus sp. Rush (unknown sp.) CAC, CRY, EUR, INU, JUN, MUL, PIN Diplacus aurantiacus Sticky monkey flower CAC, CRA, EUR, INU, MEG, PIN Rosa californica CA wild rose CAC, CRA, MEG, QUM, RAM. RIP Salix sp. Willow (unknown sp.) CRA, CRY, LAC, PSE, ROS, OAK Quercus agrifolia Coast live oak CAC, CRA, OAK, SYR, WAL Heteromeles arbutifolia Toyon CAC*, CRA, CRY, HED, OAK Baccharis salicifolia Mulefat ASP, KELxCRY, ROS, OAK Sambucus mexicana Mexican elderberry CRA, PAL, QUE, RAS Populus fremontii Fremont cottonwood ACE, PSE, ROS Ceanothus thyrsiflorus Blue blossom CAC, MUL, NIC Quercus lobata Valley oak CAC, QUE, PSY Many species from Artemisia californica California sagebrush CRA, INU, PAL Acer negundo Boxelder maple CAC, MUL preferentially Frangula californica Coffeeberry CAC, MUL sampled hosts: Quercus douglasiana Blue oak CAC, OCC Dead plant (unknown sp.) Empty planting site CAC, ROS - Mugwort Salicornia pacifica Pickleweed HUM, HUMxINU - Toyon Baccharis glutinosa Salt marsh baccharis MUL, OAK - Monkey flower Umbellularia californica Bay laurel MUL, OCC - Oak spp. Sambucus sp. Elderberry MUL, ROS Platanus racemosa Sycamore ROS, OAK Aesculus californica Buckeye CAC Also many species Alnus rhombifolia White Alder CAC Euthamia occidentalis Goldenrod CAC from: Prunus ilicifolia Holly-leaf cherry CAC - Willow Rubus ursinus CA blackberry CAC Symphoricarpos laevigatus Snowberry CAC - Juncus sp. Quercus wislizenii Canyon live oak PIN - Mulefat Aster chilensis Chilean aster Baccharis pilularis Coyote brush Clematis ligusticifolia Virgin's bower Helenium bignonia Sneezeweed Lepechinia calycina Pitcher sage Quercus sp. Oak (unknown sp.) Rhamnus crocea Redberry buckthorn Sambucus racemosa Red elderberry P. acerina, ACE; P. asparagi, ASP; P. cactorum, CAC, P. chlamydospora, CHL; P. crassamura, CRA; P. europaea, EUR; P. hedraiandra, HED; P. hydropathica, HYD; P. humicola, HUM; P. humicola x inundata, HUMxINU; P. inundata, INU; P. sp. kelmania, KEL; P. lacustris, LAC; P. megasperma species complex, MEG; P. multivora, MUL; P. nicotianae, NIC; P. occultans, OCC; P. palmivora, PAL; P. parsiana, PAR; P. pini, PIN; P. polonica X aff. "Maryland 8," POLxMAR; P. pseudocryptogea, PCY; P. pseudosyringae, PSE; P. psychrophila, PSY; P. quercetorum, QUM; P. quercina, QUE; P. ramorum, RAM; P. riparia, RIP; P. rosacearum, ROS; P. syringae, SYR; P. taxon casuarina, CAS; P. taxon juncus (sp. nov.), JUN; P. taxon mugwort (sp. nov.), MUG; P. taxon oaksoil, OAK; P. taxon raspberry, RAS; P. taxon walnut, WAL; P. thermophila, THE; P. thermophila X amnicola, THExAMN *All Phytophthora positive samples included this Psp.

8 Phytophthora species recovered, by site Site ID Year(s) planted Total samples Positive samples % positive samples Number Psp. Phytophthora spp. GUAD CHL, CRA, HYD, INU, LAC, PAR, PCY, POLxMAR, ROS, CAS, OAK, THE, THExAMN GU1A ACE, ASP, CRA, KEL, LAC, MUL, PCY, PSE, ROS, OAK, WAL UPC CAC, CRA, INU, MEG, PAL, PIN GRCE CAC, HED, MUL, PIN, OAK STMC CAC, MUL, PIN, PSY, QUE, OAK ADOB CAC, MUL, NIC, RAS CARA CAC, EUR, MUL, PIN JACB CAC, MUL, OCC STSU CAC, CRA, HED COPAR EUR, MUL, JUN PAJ INU, RAM, RIP TOMA MUG, QUM, ROS CSS CAC, PCY STRP CAC, HED ADOB CAC, CRA PENT CRA, SYR COYM HUM, HUMxINU JACA CAC STWA CAC STWB CAC STWC CAC TAR CAC CCR s MUL CALE CCR s GCBH LEND LEND LEND TIC TOCA P. cactorum most common and widespread species P. acerina, ACE; P. asparagi, ASP; P. cactorum, CAC, P. chlamydospora, CHL; P. crassamura, CRA; P. europaea, EUR; P. hedraiandra, HED; P. hydropathica, HYD; P. humicola, HUM; P. humicola x inundata, HUMxINU; P. inundata, INU; P. sp. kelmania, KEL; P. lacustris, LAC; P. megasperma species complex, MEG; P. multivora, MUL; P. nicotianae, NIC; P. occultans, OCC; P. palmivora, PAL; P. parsiana, PAR; P. pini, PIN; P. polonica X aff. "Maryland 8," POLxMAR; P. pseudocryptogea, PCY; P. pseudosyringae, PSE; P. psychrophila, PSY; P. quercetorum, QUM; P. quercina, QUE; P. ramorum, RAM; P. riparia, RIP; P. rosacearum, ROS; P. syringae, SYR; P. taxon casuarina, CAS; P. taxon juncus (sp. nov.), JUN; P. taxon mugwort (sp. nov.), MUG; P. taxon oaksoil, OAK; P. taxon raspberry, RAS; P. taxon walnut, WAL; P. thermophila, THE; P. thermophila X amnicola, THExAMN

9 Phytophthora species recovered, by site Site ID Year(s) planted Total samples Positive samples % positive samples Number Psp. Phytophthora spp. GUAD CHL, CRA, HYD, INU, LAC, PAR, PCY, POLxMAR, ROS, CAS, OAK, THE, THExAMN GU1A ACE, ASP, CRA, KEL, LAC, MUL, PCY, PSE, ROS, OAK, WAL UPC CAC, CRA, INU, MEG, PAL, PIN GRCE CAC, HED, MUL, PIN, OAK STMC CAC, MUL, PIN, PSY, QUE, OAK ADOB CAC, MUL, NIC, RAS CARA CAC, EUR, MUL, PIN JACB CAC, MUL, OCC STSU CAC, CRA, HED COPAR EUR, MUL, JUN PAJ INU, RAM, RIP TOMA MUG, QUM, ROS CSS CAC, PCY STRP CAC, HED ADOB CAC, CRA PENT CRA, SYR COYM HUM, HUMxINU JACA CAC STWA CAC STWB CAC STWC CAC TAR CAC CCR s MUL CALE CCR s GCBH LEND LEND LEND TIC TOCA species between two sites on the Guadalupe river P. acerina, ACE; P. asparagi, ASP; P. cactorum, CAC, P. chlamydospora, CHL; P. crassamura, CRA; P. europaea, EUR; P. hedraiandra, HED; P. hydropathica, HYD; P. humicola, HUM; P. humicola x inundata, HUMxINU; P. inundata, INU; P. sp. kelmania, KEL; P. lacustris, LAC; P. megasperma species complex, MEG; P. multivora, MUL; P. nicotianae, NIC; P. occultans, OCC; P. palmivora, PAL; P. parsiana, PAR; P. pini, PIN; P. polonica X aff. "Maryland 8," POLxMAR; P. pseudocryptogea, PCY; P. pseudosyringae, PSE; P. psychrophila, PSY; P. quercetorum, QUM; P. quercina, QUE; P. ramorum, RAM; P. riparia, RIP; P. rosacearum, ROS; P. syringae, SYR; P. taxon casuarina, CAS; P. taxon juncus (sp. nov.), JUN; P. taxon mugwort (sp. nov.), MUG; P. taxon oaksoil, OAK; P. taxon raspberry, RAS; P. taxon walnut, WAL; P. thermophila, THE; P. thermophila X amnicola, THExAMN

10 Juncus sp: P. multivora, P. pini Willow sp: P. crassamura, P. pseudocryptogea, P. lacustris, P. pseudosyringae, P. rosacearum, P. taxon oaksoil Juncus sp: P. pseudocryptogea Mugwort: P. chlamydospora, P. crassamura, P. hydropathica, P. inundata, P. lacustris, P. polonica X aff. "Maryland 8", P. taxon casuarina, P. thermophila X amnicola Toyon: P. cactorum, P. crassamura, P. hedraiandra

11 All Phytophthora species # sites # Plant species Clade P. acerina P. asparagi P. cactorum P. chlamydospora P. crassamura P. europaea P. hedraiandra P. humicola P. humicola X inundata P. hydropathica P. inundata P. lacustris P. megasperma species complex P. multivora P. nicotianae P. occultans P. palmivora P. parsiana P. pini P. polonica X aff. "Maryland 8" P. pseudocryptogea P. pseudosyringae P. psychrophila P. quercetorum P. quercina P. ramorum P. riparia P. rosacearum P. syringae P. sp. kelmania P. taxon casuarina P. taxon juncus (sp. nov.) 1 1? P. taxon mugwort (sp. nov.) 1 1? P. taxon oaksoil P. taxon raspberry P. taxon walnut P. thermophila P. thermophila X amnicola Phytophthora species 28 good species - 6 described since described since the project started in August 5 described but provisional 3 putative hybrids 2 novel species P. cactorum, P. multivora and P. crassamura most widespread

12 So many species About 1/4 of the ~150 species of Phytophthora All subgeneric clades represented except 5 and 10 Big, lingering question: How many of our 38 species truly came from the nurseries? Baiting a comparable amount of bulk soil from Big Sur forests resulted in 6 species (TBB, unpublished) A combined effort over more than a decade of nursery, landscape and riparian isolations across Europe produced a list of ~60 species (Jung et al. 2014)

13 P. asparagi & P. crassamura from declining maquis Declining native vegetation on Maddalena Archipelago (Scanu et al. 2015) Dieback of Quercus ilex, Asparagus albus, Cistus sp., Juniperus phoenicea, J. oxycedrus, Pistacia lentiscus and Rhamnus alaternus Several species of Phytophthora associated P. asparagi most commonly isolated & most virulent on Juniperus seedlings P. crassamura and P. ornamentata described as novel species

14 crassamura means thick walled (Scanu et al. 2015)

15 Fig 1. Symptoms of decline on Mediterranean maquis vegetation caused by Phytophthora spp.: a. Dead and dying trees of Juniperus phoeniceae with abnormal production of epicormic shoots; b. Mature tree of Juniperus oxycedrus showing severe wilting and red discoloration; c. Young tree of J. oxycedrus with red/bronze colour of foliage over the entire crown; d. Basal phloem lesion on a juniper tree extending up from below ground level; e. Collar and root rot on a young juniper tree; f. Extensive dieback and mortality of Pistacia lentiscus across site; g. Dieback and wilting of Asparagus albus. (Scanu et al. 2015)

16 Phytophthora quercina Species first isolated from declining oaks in Central & Southern Europe in the 1990s Most common Phytophthora in declining Central European oak forests, especially where trees die rapidly and in groups Fine-root pathogen, specific to the genus Quercus, but found in nursery soil with other plant species Aggressive on all Quercus species tested Balci et al. found a close relative, P. sp. ohioensis from eastern US oak stands, but P. quercina has not been isolated in North America APHIS ranked listed P. quercina as the #1 Phytophthora species of concern for introduction into the US Declining Q. robur showing different levels of crown dieback and chlorosis (specific symptom on calcaric soils due to advanced fine root destructions caused by P. citricola and P. quercina). Aggressiveness of P. quercina to Q. robur roots in a soil infestation test after 6 months; left: control, right: infested soil.

17 P. quercina isolation in Santa Clara Co. Isolated from four Valley Oaks (Q. lobata); site planted in 2002 Initial isolation is the only documented baiting of P. quercina by pear; subsequent isolations were only successful with Q. robur and Q. ilex leaf bait This represents the first detection of P. quercina in the US, confirmed by USDA

18 Ongoing work Follow-up, including treatment of most critical areas (SCVWD & Phytosphere taking the lead) Collaboration with CalPhytos working group and other researchers Culture-independent techniques with frozen soil samples DNA has been extracted from most soil samples Oomycete DNA can be detected w/ specific primers in all samples tested Systematic studies of interesting strains

19 Clade 1 Clade 7 Two novel species of Phytophthora were isolated P. taxon juncus P. taxon mugwort Neither could be unambiguously placed into a subgeneric clade, even with multiple (up to 6) loci The nature of the project raises important questions about their status as native or exotic pathogens

20 Sporangia of P. taxon mugwort

21 The big picture Increased regulations following SOD have been largely successful for foliar Phytophthora species, less so for soil-borne species Move differently, symptoms less diagnostic Regulated differently Well-meaning environmental regulations may have led to poor choices for restoration in regards to root-associated Phytophthora Choice of nursery-origin transplants rather than seeds or natural regeneration Year-round irrigation of plants adapted to Mediterranean climates Direct movement of soil for the purposes of moving unculturable plant-mutualistic microbes Oomycete diversity remains undersampled at many scales

22 Acknowledgments Santa Clara Valley Water District & employees Noah Luecke & Miles lab (CSUMB) Rino Oguchi & Valerie Wuerz, UC Davis