Phytophthora kernoviae oospore maturity, germination, and infection

Widmer, Timothy L.

doi:10.1016/j.funbio.2010.06.001

Cited by 17 publications

(15 citation statements)

References 27 publications

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“…K. latifolia has been postulated to be a potentially important host in the eastern United States for P. ramorum should it be come established there (42). The viability of the oospores was not tested in this study but their appearance was similar to that observed in cultures in a previous test (46). Oospores in fallen leaves were found to be im portant in the survival and build up of soil populations of P. cactorum (25) and P. syringae in apple orchards (24) and should be considered similar with P. kernoviae.…”

Section: Discussionmentioning

confidence: 78%

Differences in Virulence and Sporulation of Phytophthora kernoviae Isolates Originating From Two Distinct Geographical Regions

Widmer

2015

Plant Disease

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Widmer, T. L. 2015. Differences in virulence and sporulation of Phytophthora kernoviae isolates originating from two distinct geographical regions. Plant Dis. 99:460-466.Phytophthora kernoviae has only been isolated from the United King dom and New Zealand. To understand what differences may exist be tween isolates from these two distinct geographical regions, virulence studies on three host plants and sporulation on host leaves were con ducted on select isolates. Three host plant species (Rhododendron ponticum. Magnolia stellata, and Annona cherimola) were inoculated individually with sporangia of six different isolates from each geograph ical region. Results showed an overall higher virulence on all three hosts from isolates originating from the United Kingdom. After inoculation, P. kernoviae sporangia and oospore formation on different host leaves were observed and compared with P. cactorum and P. syringae. Results were host dependent, with P. kernoviae producing generally similar or higher amounts of both propagules compared with the other U.S. indig enous species. These results have implications for regulatory agencies and scientists who are interested in preventing its entrance into the United States and learning more about its potential spread.Movement and introductions of crops and plants into a new area has the potential to both move exotic pathogens into that area and expose new hosts to previously noncharacterized indigenous plant pathogens.

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Section: Discussionmentioning

confidence: 78%

Differences in Virulence and Sporulation of Phytophthora kernoviae Isolates Originating From Two Distinct Geographical Regions

Widmer

2015

Plant Disease

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“…Widmer (2010) used both germination and ability to stain in tetrazolium bromide as the criteria for Phytophthora kernoviae oospore maturity. He found that the latter plateaued after ca.…”

Section: Discussionmentioning

confidence: 99%

Decline in vitality of propagules of Phytophthora pluvialis and Phytophthora kernoviae and their inability to contaminate or colonise bark and sapwood in Pinus radiata export log simulation studies

Hood

Williams

Dick

et al. 2014

N.Z. j. of For. Sci.

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Background: Phytophthora pluvialis Reeser, W.L. Sutton & E.M. Hansen is the cause of a newly described disease, red needle cast, in certain stands of Pinus radiata D. Don in New Zealand that experience periodic foliage browning, while Phytophthora kernoviae Brasier, Beales & Kirk is also infrequently isolated from symptomatic needles. Methods: Studies were undertaken to test the possibility that these species may be transported on pine logs either as superficial contaminants or as colonists of bark or wood.Results: Pine-needle baiting found no evidence of Phytophthora species in bark samples or aqueous bark washes from stems of 603 symptomatic trees in 17 affected stands implying that survival after natural deposition of sporangia or zoospores is low or absent. The persistence of zoospores or oospores was evaluated at intervals after applying them at artificially high surface densities to the bark on log segments and incubating at five temperatures between 15°C and 35°C in the laboratory. The ability to re-isolate Phytophthora kernoviae decreased with time and increasing temperature, but this species was still obtained at low frequencies after 4 weeks at 15°C and 20°C following treatment with oospores of Phytophthora kernoviae. Phytophthora pluvialis could not be isolated under any conditions of time or temperature tested. Percentage vitality of oospores of both species as determined using tetrazolium bromide vital staining also decreased with time, although some oospores of both species remained alive after 4 weeks at all temperatures tested. In a further study to test potential log colonisation, Phytophthora spp. were not isolated from bark or xylem at or near points where zoospores, oospores or mycelium of either species were applied to the bark or sapwood of pine segments and incubated for 6 weeks under ambient or humid conditions at 17°C. Conclusion:The results of these studies suggest that occurrence of Phytophthora kernoviae or Phytophthora pluvialis on export logs from affected stands is negligible. In addition, although some remained alive, the substantial decline in vitality among artificially applied oospores implies that the survival of any few that may be naturally present on logs is likely to be slight. Based on the evidence from this work there appears to be little risk of transporting these Phytophthora species on New Zealand radiata pine logs.

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“…The known host range of P. kernoviae currently includes over 30 species (Widmer 2010). The pathogen was first discovered in historic woodland gardens in Cornwall in autumn 2003 as part of the Department for Environment, Food and Rural Affairs (Defra) and the Forestry Commission's campaign to eradicate another recently introduced pathogen, P. ramorum, the causal agent of sudden oak death.…”

Section: Introductionmentioning

confidence: 99%

Development of a real-time PCR assay for detection of Phytophthora kernoviae and comparison of this method with a conventional culturing technique

et al. 2011

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Phytophthora kernoviae is a recently described pathogen causing leaf blight, aerial dieback and bleeding cankers on trees and shrubs in parts of Great Britain and Ireland and recently reported in New Zealand. This paper describes the development of a TaqMan real-time PCR assay based on internal transcribed spacer (ITS) sequence to aid diagnosis of this pathogen in culture and in plant material. The assay showed no cross reaction with 29 other Phytophthora species, including the closely related species P. boehmeriae, and detected at least 1.2 pg of P. kernoviae DNA per reaction. A rapid and simple method can be used to extract DNA prior to testing by real-time PCR, and a plant internal control assay can be used to aid interpretation of negative results. A comparison of real-time PCR and plating for 526 plant samples collected in the UK indicated that this assay is suitable for use in routine screening for P. kernoviae.

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Phytophthora kernoviae oospore maturity, germination, and infection

Cited by 17 publications

References 27 publications

Differences in Virulence and Sporulation of Phytophthora kernoviae Isolates Originating From Two Distinct Geographical Regions

Differences in Virulence and Sporulation of Phytophthora kernoviae Isolates Originating From Two Distinct Geographical Regions

Decline in vitality of propagules of Phytophthora pluvialis and Phytophthora kernoviae and their inability to contaminate or colonise bark and sapwood in Pinus radiata export log simulation studies

Development of a real-time PCR assay for detection of Phytophthora kernoviae and comparison of this method with a conventional culturing technique

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