scholarly journals PhytophthoraSpecies Are Common on Nursery Stock Grown for Restoration and Revegetation Purposes in California

Plant Disease ◽  
2019 ◽  
Vol 103 (3) ◽  
pp. 448-455 ◽  
Author(s):  
S. Rooney-Latham ◽  
C. L. Blomquist ◽  
K. L. Kosta ◽  
Y. Y. Gou ◽  
P. W. Woods
Keyword(s):  
North America ◽  
Phytophthora Species ◽  
Molecular Techniques ◽  
Crown Rot ◽  
Native Plant ◽  
Nursery Stock ◽  
Plant Nursery ◽  
Root And Crown Rot ◽  
Symptomatic Tissue ◽  
First Time

Phytophthora tentaculata was detected for the first time in North America in 2012 in a nursery on sticky monkeyflower plant (Diplacus aurantiacus) and again in 2014 on outplanted native plants. At that time, this species was listed as a federally actionable and reportable pathogen by the USDA. As a result of these detections, California native plant nurseries were surveyed to determine the prevalence of Phytophthora species on native plant nursery stock. A total of 402 samples were collected from 26 different native plant nurseries in California between 2014 and 2016. Sampling focused on plants with symptoms of root and crown rot. Symptomatic tissue was collected and tested by immunoassay, culture, and molecular techniques (PCR). Identifications were made using sequences from the internal transcribed spacer (ITS) rDNA region, a portion of the trnM-trnP-trnM, or the atp9-nad9 mitochondrial regions. Phytophthora was confirmed from 149 of the 402 samples (37%), and from plants in 22 different host families. P. tentaculata was the most frequently detected species in our survey, followed by P. cactorum and members of the P. cryptogea complex. Other species include P. cambivora, P. cinnamomi, P. citricola, P. hedraiandra, P. megasperma, P. multivora, P. nicotianae, P. niederhauserii, P. parvispora, P. pini, P. plurivora, and P. riparia. A few Phytophthora sequences generated from mitochondrial regions could not be assigned to a species. Although this survey was limited to a relatively small number of California native plant nurseries, Phytophthora species were detected from three quarters of them (77%). In addition to sticky monkeyflower, P. tentaculata was detected from seven other hosts, expanding the number of associated hosts. During this survey, P. parvispora was detected for the first time in North America from symptomatic crowns and roots of the nonnative Mexican orange blossom (Choisya ternata). Pathogenicity of P. parvispora and P. nicotianae was confirmed on this host. These findings document the widespread occurrence of Phytophthora spp. in native plant nurseries and highlight the potential risks associated with outplanting infested nursery-grown stock into residential gardens and wildlands.

scholarly journals Phytophthora Introductions in Restoration Areas: Responding to Protect California Native Flora from Human-Assisted Pathogen Spread

Forests ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1291
Author(s):  
Susan J. Frankel ◽  
Christa Conforti ◽  
Janell Hillman ◽  
Mia Ingolia ◽  
Alisa Shor ◽  
...  
Keyword(s):  
Work Group ◽  
Pilot Project ◽  
Phytophthora Species ◽  
Plant Production ◽  
Native Plant ◽  
Collective Actions ◽  
Hybrid Species ◽  
Native Flora ◽  
Nursery Stock ◽  
Plant Nursery

Over the past several years, plantings of California native plant nursery stock in restoration areas have become recognized as a pathway for invasive species introductions, in particular Phytophthora pathogens, including first in the U.S. detections (Phytophthora tentaculata, Phytophthora quercina), new taxa, new hybrid species, and dozens of other soilborne species. Restoration plantings may be conducted in high-value and limited habitats to sustain or re-establish rare plant populations. Once established, Phytophthora pathogens infest the site and are very difficult to eradicate or manage—they degrade the natural resources the plantings were intended to enhance. To respond to unintended Phytophthora introductions, vegetation ecologists took a variety of measures to prevent pathogen introduction and spread, including treating infested areas by solarization, suspending plantings, switching to direct seeding, applying stringent phytosanitation requirements on contracted nursery stock, and building their own nursery for clean plant production. These individual or collective actions, loosely coordinated by the Phytophthoras in Native Habitats Work Group ensued as demands intensified for protection from the inadvertent purchase of infected plants from commercial native plant nurseries. Regulation and management of the dozens of Phytophthora species and scores of plant hosts present a challenge to the state, county, and federal agriculture officials and to the ornamental and restoration nursery industries. To rebuild confidence in the health of restoration nursery stock and prevent further Phytophthora introductions, a voluntary, statewide accreditation pilot project is underway which, upon completion of validation, is planned for statewide implementation.

scholarly journals First Report of Phytophthora citrophthora on Penstemon barbatus in Italy

Plant Disease ◽  
2006 ◽  
Vol 90 (9) ◽  
pp. 1260-1260 ◽  
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
D. Minerdi ◽  
M. L. Gullino
Keyword(s):  
Its Region ◽  
The United States ◽  
Phytophthora Species ◽  
Crown Rot ◽  
Pathogenicity Test ◽  
Phytophthora Citrophthora ◽  
First Report ◽  
Blastn Analysis ◽  
Root And Crown Rot ◽  
Pathogenicity Tests

Penstemon barbatus (Cav.) Roth (synonym Chelone barbata), used in parks and gardens and sometimes grown in pots, is a plant belonging to the Scrophulariaceae family. During the summers of 2004 and 2005, symptoms of a root rot were observed in some private gardens located in Biella Province (northern Italy). The first symptoms resulted in stunting, leaf discoloration followed by wilt, root and crown rot, and eventually, plant death. The diseased tissue was disinfested for 1 min in 1% NaOCl and plated on a semiselective medium for Oomycetes (4). The microorganism consistently isolated from infected tissues, grown on V8 agar at 22°C, produced hyphae with a diameter ranging from 4.7 to 5.2 μm. Sporangia were papillate, hyaline, measuring 43.3 to 54.4 × 26.7 to 27.7 μm (average 47.8 × 27.4 μm). The papilla measured from 8.8 to 10.9 μm. These characteristics were indicative of a Phytophthora species. The ITS region (internal transcribed spacer) of rDNA was amplified using primers ITS4/ITS6 (3) and sequenced. BLASTn analysis (1) of the 800 bp obtained showed a 100% homology with Phytophthora citrophthora (R. & E. Sm.) Leonian. The nucleotide sequence has been assigned GenBank Accession No. DQ384611. For pathogenicity tests, the inoculum of P. citrophthora was prepared by growing the pathogen on autoclaved wheat and hemp kernels (2:1) at 25°C for 20 days. Healthy plants of P. barbatus cv. Nano Rondo, 6 months old, were grown in 3-liter pots (one plant per pot) using a steam disinfested substrate (peat/pomix/pine bark/clay 5:2:2:1) in which 200 g of kernels per liter of substrate were mixed. Noninoculated plants served as control treatments. Three replicates were used. Plants were maintained at 15 to 20°C in a glasshouse. The first symptoms, similar to those observed in the gardens, developed 21 days after inoculation, and P. citrophthora was consistently reisolated from infected plants. Noninoculated plants remained healthy. The pathogenicity test was carried out twice with similar results. A nonspecified root and crown rot of Penstemon spp. has been reported in the United States. (2). To our knowledge, this is the first report of P. citrophthora on P. barbatus in Italy as well as in Europe. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997 (2) F. E. Brooks and D. M. Ferrin. Plant Dis. 79:212, 1995. (3) D. E. L. Cooke and J. M. Duncan. Mycol. Res. 101:667, 1997. (4) H. Masago et al. Phytopathology 67:425, 1977.

An accreditation program to produce native plant nursery stock free of Phytophthora for use in habitat restoration

2021 ◽  
Author(s):  
Tedmund J. Swiecki ◽  
Elizabeth A. Bernhardt ◽  
Susan J. Frankel ◽  
Diana Benner ◽  
Janell Hillman
Keyword(s):  
Best Management Practices ◽  
Habitat Restoration ◽  
Management Practices ◽  
Pilot Program ◽  
Native Plant ◽  
Best Management ◽  
Nursery Stock ◽  
Plant Nursery ◽  
Nursery Production ◽  
Integrated Program

Widespread Phytophthora infections have been discovered in nursery stock used in California restoration plantings. In response, nursery Phytophthora best management practices (NPBMPs) designed to exclude Phytophthora from nursery plants were developed to address the need for clean planting stock in restoration projects. A pilot program to implement the systematic use of the NPBMPs, Accreditation to Improve Restoration (AIR), was developed and started in 2018. As of 2020, 13 northern California restoration nurseries have been evaluated and five have met all the program requirements. In 564 tests conducted over four years with a sensitive leachate baiting protocol, no Phytophthora was detected from over 20,000 nursery plants produced in compliance with the NPBMPs. In comparison, Phytophthora was detected in 25% of tests conducted on partially-compliant stock, and in 71% of tests from nurseries following few or no NPBMPs. The AIR pilot program has demonstrated that container stock free of detectable Phytophthora can be reliably produced by adhering to an integrated program of clean nursery production practices. To obtain Phytophthora-free plants for habitat restoration, informed clients were willing to pay increased costs required to produce NPBMP-compliant nursery stock.

NEW RECORDS OF EUROPEAN PILOPHORUS AND ORTHOTYLUS IN CANADA (HETEROPTERA: MIRIDAE)

1982 ◽  
Vol 114 (3) ◽  
pp. 283-287 ◽  
Author(s):  
Leonard A. Kelton
Keyword(s):  
Nova Scotia ◽  
North America ◽  
New Records ◽  
European Species ◽  
Nursery Stock ◽  
First Time ◽  
Nearctic Region

This note deals with three European species of Orthotylinae now known to occur in Canada. Pilophorus confusus was discovered in 1976 in Nova Scotia and is reported for the first time from the Nearctic region. Additional distribution records are given for Orthotylus nassatus and O. viridinervis previously reported from North America by Henry (1977) and Henry and Wheeler (1979), respectively. The three species were likely introduced accidentally into this country some time ago with nursery stock importations but remained undetected until recently. They are predatory and overwinter in the egg stage. The adults of the three species are illustrated.

scholarly journals Phytophthora Species Associated with Crown and Root Rot of Apple in Chile

Plant Disease ◽  
2001 ◽  
Vol 85 (6) ◽  
pp. 603-606 ◽  
Author(s):  
B. A. Latorre ◽  
M. E. Rioja ◽  
W. F. Wilcox
Keyword(s):  
Central Valley ◽  
Phytophthora Species ◽  
Crown Rot ◽  
Apple Rootstocks ◽  
Apple Trees ◽  
Potting Medium ◽  
Root And Crown Rot ◽  
Genotype Interaction ◽  
Crown And Root Rot ◽  
Isolated Species

Phytophthora cactorum, P. cryptogea, P. gonapodyides, and P. megasperma were isolated from necrotic root and crown tissues or the rhizospheres of apple trees exhibiting typical symptoms of Phytophthora root and crown rot in the Central Valley of Chile. Representative isolates of all four species were pathogenic on a variety of apple rootstocks and scions in trials conducted on excised shoots and 1-year-old MM.106 rootstock grown for 4 months in infested potting medium. P. cactorum was the most frequently isolated species and the most virulent in pot tests, although a significant Phytophthora sp.-apple genotype interaction was observed. This is the first report of any species other than P. cactorum causing root and crown rot of apple trees in Chile.

scholarly journals Resistance to Phytophthora Species among Rootstocks for Cultivated Prunus Species

HortScience ◽  
2017 ◽  
Vol 52 (11) ◽  
pp. 1471-1476 ◽  
Author(s):  
Gregory T. Browne
Keyword(s):  
Root Rot ◽  
Phytophthora Species ◽  
Crown Rot ◽  
Phytophthora Cactorum ◽  
Prunus Species ◽  
Phytophthora Megasperma ◽  
Soil Flooding ◽  
Root And Crown Rot ◽  
Crown And Root Rot ◽  
Multiple Species

Many species of Phytophthora de Bary are important pathogens of cultivated Prunus L. species worldwide, often invading the trees via their rootstocks. In a series of greenhouse trials, resistance to Phytophthora was tested in new and standard rootstocks for cultivated stone fruits, including almond. Successive sets of the rootstocks, propagated as hardwood cuttings or via micropropagation, were transplanted into either noninfested potting soil or potting soil infested with Phytophthora cactorum (Lebert & Cohn) J. Schöt., Phytophthora citricola Sawada, Phytophthora megasperma Drechs, or Phytophthora niederhauserii Z.G. Abad & J.A. Abad. Soil flooding was included in all trials to facilitate pathogen infection. In some trials, soil flooding treatments were varied to examine their effects on the rootstocks in both the absence and presence of Phytophthora. Two to 3 months after transplanting, resistance to the pathogens was assessed based on the severity of root and crown rot. ‘Hansen 536’ was consistently more susceptible than ‘Lovell’, ‘Nemaguard’, ‘Atlas’, ‘Viking’, ‘Citation’, and ‘Marianna 2624’ to root and/or crown rot caused by P. cactorum, P. citricola, and P. megasperma. By contrast, susceptibility to P. niederhauserii was similarly high among all eight tested genotypes of peach, four genotypes of peach × almond, two genotypes of (almond × peach) × peach, and one genotype of plum × almond. Most plum hybrids were highly and consistently resistant to crown rot caused by P. niederhauserii, but only ‘Marianna 2624’ was highly resistant to both crown and root rot caused by all of the Phytophthora species. The results indicate that there is a broad tendency for susceptibility of peach × almond rootstocks and a broad tendency for resistance of plum hybrid rootstocks to multiple species of Phytophthora.

scholarly journals Phytophthora Root and Collar Rot of Paulownia, a New Disease for Europe

Forests ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1664
Author(s):  
Francesco Aloi ◽  
Mario Riolo ◽  
Federico La Spada ◽  
Gaetano Bentivenga ◽  
Salvatore Moricca ◽  
...  
Keyword(s):  
Irrigation Management ◽  
Morphological Characteristics ◽  
Stem Bark ◽  
Phytophthora Species ◽  
Crown Rot ◽  
Infested Soil ◽  
Soil P ◽  
Rdna Its ◽  
Rdna Its Sequences ◽  
Root And Crown Rot

Paulownia species are fast growing trees native to China, which are being grown in managed plantings in several European countries for the production of wood and biomasses. In 2018, wilting, stunting, leaf yellowing, and collapse, as a consequence of root and crown rot, were observed in around 40% of trees of a 2-year-old planting of Paulownia elongata × P. fortunei in Calabria (Southern Italy). Two species of Phytophthora were consistently recovered from roots, basal stem bark, and rhizosphere soil of symptomatic trees and were identified as Ph. nicotianae and Ph. palmivora on the basis of both morphological characteristics and phylogenetic analysis of rDNA ITS sequences. Koch’s postulates were fulfilled by reproducing the symptoms on potted paulownia saplings transplanted into infested soil or stem-inoculated by wounding. Both Phytophthora species were pathogenic and caused root rot and stem cankers. Even though P. palmivora was the only species recovered from roots of naturally infected plants, in pathogenicity tests through infested soil P. nicotianae was more virulent. This is the first report of Phytophthora root and crown rot of a Paulownia species in Europe. Strategies to prevent this emerging disease include the use of healthy nursery plants, choice of well-drained soils for new plantations, and proper irrigation management.

scholarly journals A New Root and Crown Rot Disease of Heath in California Caused by Cylindrocladium pauciramosum

Plant Disease ◽  
1999 ◽  
Vol 83 (6) ◽  
pp. 589-589 ◽  
Author(s):  
S. T. Koike ◽  
D. M. Henderson ◽  
P. W. Crous ◽  
C. L. Schoch ◽  
S. A. Tjosvold
Keyword(s):  
North America ◽  
Species Complex ◽  
Ground Cover ◽  
First Record ◽  
Crown Rot ◽  
Conidial Suspension ◽  
Similar Disease ◽  
Crown Tissue ◽  
Root And Crown Rot ◽  
Rot Disease

Heath (Erica capensis Salter) is a woody, evergreen plant used in Cali-fornia as a landscape shrub or ground cover. In 1997, a new root and crown disease was found in commercial nursery plantings of potted heath. A similar disease was found in 1998 on heath transplants being grown as liners. In both situations, roots were necrotic and crown tissue turned brown. Affected plants became gray-green in color, withered, and died. A Cylindrocladium species was consistently isolated from roots, crowns, and lower stems of symptomatic plants. Isolates were characterized by having penicillate conidiophores terminating in obpyriform to broadly ellipsoidal vesicles. Conidia were hyaline, 1-septate, straight with rounded ends, (30-) 45 to 55 (-60) × (3.5-) 4 to 5 μm, placing it in the Cylindrocladium candelabrum Viégas species complex. Ten single-conidial isolates produced perithecia with viable progeny of Calonectria pauciramosa C.L. Schoch & Crous when mated on carnation leaf agar with tester strains of Cylindrocladium pauciramosum C.L. Schoch & Crous (1). Matings with tester strains of all other species in this complex proved unsuccessful. Pathogenicity of 8 representative isolates was confirmed by applying 3 ml of a conidial suspension (3.0 × 105 conidia per ml) to the crowns of potted, 6-month-old, rooted heath cuttings that were subsequently maintained in a greenhouse (23 to 25°C). After 2 weeks, plant crowns and roots developed symptoms similar to those observed in the field, and plants later wilted and died. C. pauciramosum was reiso-lated from all plants. Control plants, which were treated with water, did not develop any symptoms. The tests were repeated and the results were similar. This is the first report of C. pauciramosum as a pathogen of heath, and the first record of this pathogen from North America. Reference: (1) C. L. Schoch et al. Mycologia 91:286, 1999.

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