Invasive Species Compendium

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Phytophthora austrocedri

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Datasheet

Phytophthora austrocedri

Summary

  • Last modified
  • 09 January 2019
  • Datasheet Type(s)
  • Invasive Species
  • Pest
  • Preferred Scientific Name
  • Phytophthora austrocedri
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Chromista
  •     Phylum: Oomycota
  •       Class: Oomycetes
  •         Order: Peronosporales
  • Summary of Invasiveness
  • Phytophthora austrocedri is a soil and water-borne oomycete pathogen of woody species residing within the Cupressaceae. Its centre of origin is unknown. It was first reported causing widespread dieback and mort...

  • Principal Source
  • Draft datasheet under review

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Pictures

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PictureTitleCaptionCopyright
Phytophthora austrocedri; mortality of Austrocedrus chilensis [Libocedrus chilensis] (Chilean cedar) in southern Argentina. November 2014.
TitleSymptoms
CaptionPhytophthora austrocedri; mortality of Austrocedrus chilensis [Libocedrus chilensis] (Chilean cedar) in southern Argentina. November 2014.
Copyright©Crown Copyright/Forest Research - All Rights Reserved
Phytophthora austrocedri; mortality of Austrocedrus chilensis [Libocedrus chilensis] (Chilean cedar) in southern Argentina. November 2014.
SymptomsPhytophthora austrocedri; mortality of Austrocedrus chilensis [Libocedrus chilensis] (Chilean cedar) in southern Argentina. November 2014.©Crown Copyright/Forest Research - All Rights Reserved
Phytophthora austrocedri; infected junipers (Juniperus communis). Northern UK. June 2013.
TitleSymptoms
CaptionPhytophthora austrocedri; infected junipers (Juniperus communis). Northern UK. June 2013.
Copyright©Crown Copyright/Forest Research - All Rights Reserved
Phytophthora austrocedri; infected junipers (Juniperus communis). Northern UK. June 2013.
SymptomsPhytophthora austrocedri; infected junipers (Juniperus communis). Northern UK. June 2013.©Crown Copyright/Forest Research - All Rights Reserved
Phytophthora austrocedri; basal lesion on juniper (Juniperus communis). UK. November 2011.
TitleSymptoms
CaptionPhytophthora austrocedri; basal lesion on juniper (Juniperus communis). UK. November 2011.
Copyright©Crown Copyright/Forest Research - All Rights Reserved
Phytophthora austrocedri; basal lesion on juniper (Juniperus communis). UK. November 2011.
SymptomsPhytophthora austrocedri; basal lesion on juniper (Juniperus communis). UK. November 2011.©Crown Copyright/Forest Research - All Rights Reserved
Phytophthora austrocedri; symptoms, causing mortality of Cupressus nootkatensis [Xanthocyparis nootkatensis] (Alaska yellow-cedar). Scotland, UK. March 2011.
TitleSymptoms
CaptionPhytophthora austrocedri; symptoms, causing mortality of Cupressus nootkatensis [Xanthocyparis nootkatensis] (Alaska yellow-cedar). Scotland, UK. March 2011.
Copyright©Crown Copyright/Forest Research - All Rights Reserved
Phytophthora austrocedri; symptoms, causing mortality of Cupressus nootkatensis [Xanthocyparis nootkatensis] (Alaska yellow-cedar). Scotland, UK. March 2011.
SymptomsPhytophthora austrocedri; symptoms, causing mortality of Cupressus nootkatensis [Xanthocyparis nootkatensis] (Alaska yellow-cedar). Scotland, UK. March 2011.©Crown Copyright/Forest Research - All Rights Reserved

Identity

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Preferred Scientific Name

  • Phytophthora austrocedri Gresl. & E.M. Hansen, 2007

Other Scientific Names

  • Phytophthora austrocedrae Greslebin, Hansen & Sutton, 2007

Summary of Invasiveness

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Phytophthora austrocedri is a soil and water-borne oomycete pathogen of woody species residing within the Cupressaceae. Its centre of origin is unknown. It was first reported causing widespread dieback and mortality of Austrocedrus chilensis [Libocedrus chilensis] in southern Argentina in 2007 and subsequently reported causing extensive dieback and mortality of Juniperus communis in northern Britain. The pathogen is considered to be invasive in both regions due to the clonal nature of the populations and recently observed disease epidemics. In addition to the two established wider-environment epidemics in Argentina and Britain, P. austrocedri has been isolated from a young Juniperus horizontalis growing in a plant nursery in Germany and from an ornamental Cupressus sempervirens located in a public park in northern Iran. P. austrocedri infects phloem in the roots and stem bases of affected hosts, with aerial infections also reported on J. communis in Britain. Natural spread is likely to occur via movement in water and soil, and possibly via animal and/or human activity. The presence of water courses and areas of standing water are likely to favour pathogen spread at a site. In Britain, DNA of P. austrocedri has been confirmed as present in traded plants of various Cupressaceae species, including those imported from continental Europe. The pathogen is a regulated pest in the plant trade in the UK.

Taxonomic Tree

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  • Domain: Eukaryota
  •     Kingdom: Chromista
  •         Phylum: Oomycota
  •             Class: Oomycetes
  •                 Order: Peronosporales
  •                     Family: Peronosporaceae
  •                         Genus: Phytophthora
  •                             Species: Phytophthora austrocedri

Notes on Taxonomy and Nomenclature

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Phytophthora austrocedri was first described by Greslebin et al. (2007). The name ‘austrocedri’ refers to Austrocedrus, the genus of conifers first recorded as a host of this pathogen in Argentina. The pathogen is also incorrectly referred to as Phytophthora austrocedrae. P. austrocedri is in clade 8d of the Martin et al. (2014) molecular phylogeny of the Phytophthora genus. Its two closest known relatives are P. syringae and P. obscura.

Description

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P. austrocedri (synonym: Phytophthora austrocedrae Gresl. & E.M. Hansen, sp. nov.) is a filamentous oomycete plant pathogen first described in 2007 from southern Argentina where it is associated with widespread mortality of the native cypress Austrocedrus chilensis [Libocedrus chilensis] (Cupressaceae) (Greslebin et al., 2007; Greslebin and Hansen, 2010). Subsequently, P. austrocedri was confirmed as the cause of extensive mortality of Juniperus communis in northern Britain (Green et al., 2012; 2015). It is a homothallic species characterized by Greslebin et al. (2007) and Henricot et al. (2017) as having semipapillate, non-caducous sporangia, oogonia with amphigynous antheridia, coralloid hyphae and very slow growth of 0.5-2 mm per day on V8 agar at an optimal temperature range of 15-17.5°C. Colonies on V8 agar have white aerial mycelium ranging from cottony, to woolly, to felty with dense or sparse mycelium and either diffused or entire margins. Isolates of P. austrocedri from Britain and Argentina show no clear differences in the dimensions of sporangia (lxb mean: 51.8 ± 0.6 x 36.4 ± 0.3 µm), oogonia (mean diameter: 38 ± 0.29 µm) or oospores (mean diameter: 32.9 ± 0.27 µm) (Greslebin and Hansen, 2010; Henricot et al., 2017). Based on analyses of nuclear and mitochondrial DNA sequences, British isolates and Argentinian isolates are genetically distinct, conforming to distinct clonal lineages of P. austrocedri (Henricot et al., 2017).

Distribution

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In addition to the wide environment outbreaks on Austrocedrus chilensis [Libocedrus chilensis] and Juniperus communis in southern Argentina and Britain, P. austrocedri has been isolated from Cupressus nootkatensis [Xanthocyparis nootkatensis] (Green et al., 2016) and Chamaecyparis lawsoniana (S Green and GA MacAskill, Forest Research, Roslin, UK, unpublished data) in a public park and private garden, respectively, in the Glasgow area of Scotland. The pathogen has also been isolated from a single young Juniperus horizontalis growing in a nursery in Germany (Werres et al., 2014) and from a single Cupressus sempervirens located in a public park in northern Iran (Mahdikhani et al., 2017). Area of origin is unknown.

Distribution Table

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The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Continent/Country/RegionDistributionLast ReportedOriginFirst ReportedInvasiveReferenceNotes

Asia

IranPresent, few occurrences2017Introduced2017 Invasive Mahdikhani et al., 2017Single report in city in northern Iran

South America

ArgentinaWidespreadIntroduced2007 Invasive Greslebin et al., 2007Established and widespread in southern Argentina

Europe

GermanyPresentIntroduced Invasive Werres et al., 2014Isolated from a single nursery plant, but not detected since 2001. Possibly present in the nursery trade
UKWidespreadIntroduced2012 Invasive Green et al., 2012Established and widespread in northern Britain

History of Introduction and Spread

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No published records exist for human-mediated introductions.

Risk of Introduction

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The isolation of P. austrocedri from J. horizontalis in a plant nursery in Germany that imported plants (Werres et al., 2014) was the first confirmation that the pathogen may be moved internationally in trade. Since 2012, when monitoring for the pathogen started in the UK, there have been numerous UK Plant Health records (based on DNA analyses) of interceptions of P. austrocedri on traded Juniperus spp., Chamaecyparis spp. and Cupressus leylandii (data provided by Science and Advice for Scottish Agriculture [SASA] and the Animal and Plant Health Agency [APHA]). Therefore, a major pathway via which P. austrocedri is likely to move (also by analogy with other Phytophthora spp.) is on ‘plants for planting’ of known natural hosts (e.g. Austrocedrus chilensis [Libocedrus chilensis], Juniperus spp., Chamaecyparis spp. and Cupressus spp.) and from countries where P. austrocedri is known to occur. P. austrocedri is a quarantine regulated pest in the UK.

Habitat

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P. austrocedri infects forest and amenity trees or woody shrub species of all ages with all known hosts limited to species within the Cupressaceae. It spreads in water and is also readily detected in soil (Elliot et al., 2015).

Habitat List

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CategorySub-CategoryHabitatPresenceStatus
Terrestrial
Terrestrial – ManagedManaged forests, plantations and orchards Principal habitat Harmful (pest or invasive)
Urban / peri-urban areas Secondary/tolerated habitat Harmful (pest or invasive)
Terrestrial ‑ Natural / Semi-naturalNatural forests Principal habitat Harmful (pest or invasive)

Hosts/Species Affected

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Based on DNA sequence analyses, P. austrocedri has been found to infect stem/roots of Cupressus torulosa and a range of Juniperus spp. (S Green and A Armstrong, Forest Research, Roslin, UK, unpublished data) as well as foliage of young traded plants of Cupressus x leylandii (J Barbrook, Animal and Plant Health Agency, York, UK, personal communication).

Symptoms

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Foliage discolouration and dieback occur over all or part of the tree crown as a result of basal lesions, which often originate from below the ground and extend up the stem, killing phloem and cambial tissues. On A. chilensis [L. chilensis], lesions caused by P. austrocedri extend in the phloem from killed roots up to 1 m up the tree bole (Greslebin and Hansen, 2010). Lesions on infected J. communis are a bright orange-brown (cinnamon) colour, sometimes with a distinct yellow colouration of phloem at the lesion margins, and may be basal (predominantly) or aerial (occasionally) (Green et al., 2015). On A. chilensis [L. chilensis], hyphae of P. austrocedri also invade the xylem ray parenchyma and fibre tracheids below phloem lesions, blocking water transport and contributing to foliage decline (Vélez et al., 2014). Latent infections have not been recorded.

List of Symptoms/Signs

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SignLife StagesType
Roots / necrotic streaks or lesions
Stems / canker on woody stem
Stems / discoloration
Stems / necrosis
Whole plant / discoloration
Whole plant / plant dead; dieback

Biology and Ecology

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Genetics

Only two genetically distinct strains of P. austrocedri have been recognized to date. One strain present in southern Argentina, which has also been isolated from J. horizontalis in Germany, is known as the ARG lineage; the strain present in Britain is known as the UK lineage (Henricot et al., 2017). In both regions the pathogen populations are clonal (Vélez et al., 2014; Henricot et al., 2017). Based on a comparison of the partial sequence of the Internal Transcribed Spacer region of ribosomal RNA, the strain of P. austrocedri isolated from C. sempervirens in Iran (Mahdikhani et al., 2017) is closer to the UK lineage than the ARG lineage.

Reproductive Biology

P. austrocedri is homothallic (self-fertile), forming abundant sexually produced oospores in colonies growing on V8 agar (Greslebin and Hansen, 2010; Henricot et al., 2017). The pathogen also reproduces asexually, forming sporangia (spore sacs) in which the free swimming zoospores develop and are released in water.

Physiology and Phenology

P. austrocedri infects its hosts via vegetative mycelia which arise from germinating zoospores or oospores. Since vegetative growth of the pathogen is inhibited at temperatures of 25°C and above (Henricot et al., 2017) higher temperatures could limit the ability of P. austrocedri to complete its life cycle. However, the production of oospores by this homothallic species could potentially allow persistence and survival in host tissues and in soil under non-optimal conditions for extended periods. This species is not known to produce chlamydospores. Its native range is not known.

Population Size and Structure

Because the centre of origin of P. austrocedri is unknown, its population size cannot be estimated. Only two clonal linages of the pathogen have so far been identified; one epidemic on A. chilensis [L. chilensis] in southern Argentina and the other epidemic on J. communis in northern Britain. Both are thought to originate from the same sexually reproducing population of unknown location (Henricot et al., 2017).

Environmental Requirements

Climate and site hydrology appear to be important factors affecting the establishment and impact of P. austrocedri, with the disease symptoms that it causes most prevalent in cool regions (Patagonia and northern Britain) and in areas of high soil moisture and poor drainage or in close proximity to watercourses (La Manna and Rajchenberg, 2004; Green et al., 2015).

Climate

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ClimateStatusDescriptionRemark
C - Temperate/Mesothermal climate Preferred Average temp. of coldest month > 0°C and < 18°C, mean warmest month > 10°C

Air Temperature

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Parameter Lower limit Upper limit
Mean maximum temperature of hottest month (ºC) 25

Means of Movement and Dispersal

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Natural Dispersal

Very little is currently known about the natural dispersal mechanisms of P. austrocedri. Based on knowledge of other Phytophthora species, natural spread is likely to occur via movement in water and soil, and possibly via animal and/or human activity. The presence of water courses and poorly drained soils with areas of standing water likely favour pathogen spread at a site (Green et al., 2015). DNA of P. austrocedri has been readily detected in soils at infected sites in Britain (Elliot et al., 2015) and the pathogen has been isolated into culture from soil using a baiting method (B Henricot, Forest Research, Roslin, UK, unpublished data). Thus, it is possible that human and large mammal activity, for example the movement of grazing livestock or wild species naturally ranging from site to site, may also assist in the introduction and spread of P. austrocedri through transfer of soil contaminated with spores from the pathogen. The potential for aerial sporulation and dispersal is unknown, but P. austrocedri has been isolated from aerial stem lesions on J. communis at several wider environment sites in Britain (Green et al., 2015) and it was isolated from an aerial lesion on C. lawsoniana in Scotland. P. austrocedri produces non-caducous sporangia, and aerial lesions have not been reported on A. chilensis [L. chilensis] infected by P. austrocedri in Argentina. In Britain, DNA of the pathogen has been detected in J. communis berries collected from a number of sites (A Armstrong et al., Forest Research, Roslin, UK, unpublished data). Since berries are eaten by birds and collected by humans for supplementary planting schemes, infected berries may be another potential route of spread of P. austrocedri both within the UK and between countries, although such a pathway has never actually been confirmed.

Vector Transmission (biotic)

Depending on the longevity of viable P. austrocedri propagules in soil, the pathogen may possibly be spread in soil on the feet of livestock, wild animals and humans, or on vehicles/equipment. There also remains the possibility of transmission by birds.

Accidental Introduction

The greatest known risk of inadvertent spread of P. austrocedri both regionally and internationally is via the plant trade, as DNA of the pathogen has been found in diseased tissues of young Juniperus species, C. lawsoniana and Cupressus x leylandii imported into Britain from other European Union countries (J Barbrook, Animal and Plant Health Agency, York, England, personal communication and A Schlenzig, Science and Advice for Scottish Agriculture, Edinburgh, Scotland, personal communication).

Pathway Causes

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CauseNotesLong DistanceLocalReferences
HorticultureP. austrocedri detected in trade nursery plants of several species of Cupressaceae Yes Yes Henricot et al., 2017

Pathway Vectors

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VectorNotesLong DistanceLocalReferences
Plants or parts of plantsNumerous UK Plant Health interceptions annually Yes Yes , ; , ; , ; ,
Soil, sand and gravelDNA of P. austrocedri detected in soil at infected sites Yes Yes Elliot et al., 2015

Economic Impact

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The host affected by P. austrocedri in southern Argentina, A. chilensis [L. chilensis], is a long-lived endemic species of the Andean forests of Patagonia distributed between 37 °7’ and 43 °44’ S over an area of about 140,000 hectares. The species is of considerable economic value, producing high quality wood used for construction and woodworking (La Manna et al., 2012). P. austrocedri is present across the native growth range of A. chilensis [L. chilensis] (Vélez et al., 2014). However, due to the uneven distribution of the disease epidemic on this host, the true economic impact of P. austrocedri is hard to estimate (La Manna et al., 2012). In Britain, J. communis is one of only three native conifer species and can be found right across the country, with one population centre on the chalk downlands of southern England, another in northern England and Scotland, and scattered populations in between (Thomas et al., 2007). P. austrocedri is now widespread on J. communis across northern Britain, with levels of mortality varying from site to site; on some sites up to 80% of the J. communis are symptomatic (Green et al., 2015). J. communis is not harvested commercially, and apart from a recent upsurge in local craft gin distilleries in Scotland, some of which harvest locally grown J. communis berries, the economic impact of the pathogen in Britain is low. The findings of P. austrocedri in Germany and Iran are single incidences with no notable impact.

Environmental Impact

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A. chilensis [L. chilensis] is an ecologically important species of native Cupressaceae in the Patagonian Andes. The impact of P. austrocedri in Argentina is high in areas of localized high mortality, including within national parks (Vélez et al., 2014). In Britain, P. austrocedri is now considered to be one of the major threats to the survival of J. communis at severely infected sites in northern Britain, including designated Sites of Special Scientific Interest (SSSI).

Impact: Biodiversity

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The impact of P. austrocedri on biodiversity in southern Argentina has not been the subject of published studies, but is thought to be high due to the widespread mortality of a long-lived native conifer species with important ecological functions (Vélez et al., 2014). In Britain, J. communis is highly valued as an important constituent of the woodland ecosystem and for this reason is listed as a priority species in the UK Biodiversity Action Plan [http://jncc.defra.gov.uk/ukbap]. The impact of P. austrocedri on biodiversity in Britain is high, as it is to be considered as additional to a general population decline of J. communis already apparent in Britain over the last sixty to seventy years due to overgrazing, burning, population fragmentation and lack of regeneration (Green et al., 2015). Juniper is also a key food plant for a wide range of invertebrates and birds in the UK, and it has a unique and specialized group of associated insects, fungi and lichens (Thomas et al., 2007).

Social Impact

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The widespread mortality of A. chilensis [L. chilensis] caused by P. austrocedri in Argentina is having an impact on its aesthetic role as a native forest species for tourists and local communities in the Argentinian Patagonian Andes (La Manna et al., 2012). In Britain, the social impact of P. austrocedri on juniper is low to medium, based on societal value of juniper as one of only three native conifer species (Green and Webber, 2015).

Risk and Impact Factors

Top of page Invasiveness
  • Proved invasive outside its native range
  • Has propagules that can remain viable for more than one year
  • Reproduces asexually
Impact outcomes
  • Damaged ecosystem services
  • Ecosystem change/ habitat alteration
  • Host damage
  • Modification of fire regime
  • Modification of successional patterns
  • Negatively impacts forestry
  • Negatively impacts livelihoods
  • Negatively impacts tourism
  • Reduced amenity values
  • Reduced native biodiversity
  • Threat to/ loss of native species
Impact mechanisms
  • Pathogenic
Likelihood of entry/control
  • Highly likely to be transported internationally accidentally
  • Difficult to identify/detect as a commodity contaminant
  • Difficult to identify/detect in the field
  • Difficult/costly to control

Diagnosis

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Tissue pieces from a phloem sample containing a lesion are processed to confirm presence of P. austrocedri by plating directly on to SMA + MRP (benomyl hydrochloride, Rifamycin, Pimaricin) Phytophthora selective medium (Brasier et al., 2005) and incubating at 15°C in darkness for up to one month to allow colony growth (Green et al., 2012; 2015). Phloem tissue can also be tested for the pathogen using a P. austrocedri-specific quantitative real-time PCR assay as described by Mulholland et al. (2013).

Detection and Inspection

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Phloem (inner bark) samples are used for diagnosis purposes. Sampling should be undertaken from a tree that is in the early to mid-stages of decline. Trees that are already dead with entirely bronzed foliage do not make suitable samples as the inner bark is invariably too dry to yield P. austrocedri in isolation. Use a sharp knife to cut away the outer bark at the base of the main stem and upper roots of an affected tree, exposing the phloem (inner bark). Look for signs of orange to brown discolouration in the phloem, which indicates phloem killing and possible infection by P. austrocedri (Green et al., 2015). If an aerial infection is suspected, cut away the outer bark at the base of affected branches to look for diseased, discoloured phloem. Live, healthy phloem is white in colour, whereas diseased phloem is dull orange-brown. If the phloem is infected, then work outwards gradually removing bark until revealing the transition between infected and healthy phloem, i.e. where the orange-brown phloem meets the healthy white phloem. This is known as the live-dead junction. With P. austrocedri the live-dead junction will often be seen as an area of healthy phloem with ‘tongues’ or strips of infected (discoloured) tissue extending into it. If diseased phloem is found, cut away several sections of phloem, each about 5-10 cm2, cutting down to the wood underneath the phloem. Make sure the sample contains the live-dead junction.

Similarities to Other Species/Conditions

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P. austrocedri is taxonomically most similar to P. syringae and P. obscura. However, there is unlikely to be confusion in field or laboratory diagnoses as these species have not been found infecting the same hosts as P. austrocedri. The extremely slow growth rate of P. austrocedri on artificial media is also a distinguishing feature (Henricot et al., 2017).

Prevention and Control

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Prevention

Statutory control of P. austrocedri should be undertaken in the international plant trade to protect individual countries and to lessen the risk of transmission to other host species. This would require destruction/sterilization of infected plants and soil.

Eradication

Current records suggest that P. austrocedri has a widespread distribution in the wider environment in southern Argentina and in northern Britain. Therefore, attempts to exclude or eradicate the pathogen by regulation would only have a limited effect, as the greatest risk of spread is from infected plants, water and soil within these countries. P. austrocedri has also been identified on young plants in nurseries where statutory eradication may be possible (Green and Webber, 2015).

Containment

Currently, for heavily infected sites in the wider environment a strategy of containment is recommended in order to protect other sites where the pathogen has not established. This involves measures to limit human or livestock-assisted spread, such as preventing the removal of plant material from infected sites, cleaning and disinfecting footwear and tools, restrictions on livestock movement following removal from site and, where appropriate, putting notices in place asking members of the public to keep to paths. It is not possible to put in place effective measures to prevent natural spread via water or movement via soil with wild animals. This will mean that the efficacy of containment measure will always be limited (Green and Webber, 2015).

P. austrocedri is already widely established in southern Argentina and in northern Britain. Non-statutory controls with the aim of conserving the main affected host trees in these regions could include targeted selection of sites for conservation measures. Based on observations of the distribution of symptoms these would include sites on freer draining soils away from watercourses where the impact of P. austrocedri is likely to be low. The greater use of rejuvenation and recovery through natural regeneration of surviving individuals at these sites is recommended rather than bringing new plants from nurseries on to site which might have a risk of carrying the disease from the nursery.

Control

There are no known effective control measures other than statutory control in nurseries and traded plants. Control of P. austrocedri, once established on a site, would require destruction and removal of all affected hosts. However, this is physically impractical in forestry or upland woodland situations.

Monitoring and Surveillance

In Britain, the use of aerial helicopter surveillance and aerial photography by the Forestry Commission has been useful in determining the extent of symptomatic J. communis, enabling ground surveyors to determine whether P. austrocedri is present. However, such efforts have not been helpful in controlling the disease.

Gaps in Knowledge/Research Needs

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There is a need to determine the area of origin of P. austrocedri so that measures can be put in place to avoid the spread of additional genotypes of the pathogen to new locations. The natural mechanisms of long distance dispersal and the viability/longevity of oospores in soil or host debris are also unknown. Modelling the current impact of P. austrocedri in relation to site factors might help to identify areas at low risk of the pathogen establishing and which, therefore, could be targeted for conservation/restoration measures.

Observations of healthy individuals of J. communis located within heavily infested sites in Britain, along with the occurrence of healthy and naturally regenerating young juniper at such sites (S Green et al., Forest Research, Roslin, UK, unpublished data), suggests that tolerance to the pathogen might exist within the J. communis population. Investigating heritable resistance within endemic populations of A. chilensis [L. chilensis] and J. communis might enable the identification of tolerant genotypes to assist with the rehabilitation of infested forests.

References

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Brasier, C. M., Beales, P. A., Kirk, S. A., Denman, S., Rose, J., 2005. Phytophthora kernoviae sp. nov., an invasive pathogen causing bleeding stem lesions on forest trees and foliar necrosis of ornamentals in the UK. Mycological Research, 109(8), 853-859. doi: 10.1017/S0953756205003357

Elliot, M., Schlenzig, A., Harris, C. M., Meagher, T. R., Green, S., 2015. An improved method for qPCR detection of three Phytophthora spp. in forest and woodland soils in northern Britain. Forest Pathology, 45(6), 537-539. http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1439-0329 doi: 10.1111/efp.12224

Green S, Webber J, 2015. Rapid Pest Risk Analysis (PRA) for: Phytophthora austocedri. Forest Research.https://secure.fera.defra.gov.uk/phiw/riskRegister/downloadExternalPra.cfm?id=4058

Green, S., Elliot, M., Armstrong, A., Hendry, S. J., 2015. Phytophthora austrocedrae emerges as a serious threat to juniper (Juniperus communis) in Britain. Plant Pathology, 64(2), 456-466. http://onlinelibrary.wiley.com/doi/10.1111/ppa.12253/full doi: 10.1111/ppa.12253

Green, S., Hendry, S. J., MacAskill, G. A., Laue, B. E., Steele, H., 2012. Dieback and mortality of Juniperus communis in Britain associated with Phytophthora austrocedrae. New Disease Reports, 26, 2. http://www.ndrs.org.uk/article.php?id=026002 doi: 10.5197/j.2044-0588.2012.026.002

Green, S., MacAskill, G. A., Dun, H., Armstrong, A. C., Henricot, B., 2016. First report of Phytophthora austrocedri infecting Nootka cypress in Britain. New Disease Reports, 33, 21. http://www.ndrs.org.uk/pdfs/033/NDR_033021.pdf doi: 10.5197/j.2044-0588.2016.033.021

Greslebin, A. G., Hansen, E. M., 2010. Pathogenicity of Phytophthora austrocedrae on Austrocedrus chilensis and its relation with mal del ciprés in Patagonia. Plant Pathology, 59(4), 604-612. http://www.blackwell-synergy.com/loi/ppa doi: 10.1111/j.1365-3059.2010.02258.x

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Links to Websites

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WebsiteURLComment
Forest Researchhttps://www.forestry.gov.uk/paustrocedrae

Principal Source

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Draft datasheet under review

Contributors

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20/08/18 Original text by:

Sarah Green, Forest Research, Northern Research Station, Roslin, Midlothian, Scotland

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