The Role of Phytophthora Cinnamomi in Australian and New Zealand Forests

Newhook, and F J; Podger, F. D.

doi:10.1146/annurev.py.10.090172.001503

Cited by 111 publications

(43 citation statements)

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“…Although Phytophthora diseases such as those caused by P. cinnamomi are generally recognised to be more frequent on soils with impeded drainage favourable to the pathogen [49,65], severe losses have also been reported on well drained soils or even dry areas [28,148]. Negative effects of drought on the development of P. cinnamomi in soil or in bark have often been reported [32,116,125,195] whereas synergistic interactions between drought and infection have been demonstrated on tree physiology and the severity of disease symptoms [20,128,129].…”

Section: Disease-or Health Status-related Variablesmentioning

confidence: 99%

Interactive effects of drought and pathogens in forest trees

et al. 2006

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-This review synthesizes the available knowledge on drought-disease interactions in forest trees with a focus on (1) evidence and patterns of drought-disease interactions, (2) current understanding of processes and mechanisms, and (3) three well documented cases studies. The first part is based on the analysis of a database of slightly more than one hundred studies, obtained by keyword searches combining drought, diseases or pathogens, and forest trees. A large majority of published studies referred to a positive association between drought and disease, i.e. disease favoured by drought or drought and disease acting synergistically on tree health status, with a predominance of canker/dieback diseases, caused by pathogens like Botryosphaeria, Sphaeropsis, Cytospora and Biscognauxia (Hypoxylon). The type of disease-related variables (incidence vs. severity) and the intensity and timing of water stress were shown to be significant factors affecting the drought-infection interaction. Interactions with other abiotic stresses and species-specific and genetic effects, related to host or pathogen, have also been reported. Direct effects of drought on pathogens are generally negative, although most fungal pathogens exhibit an important plasticity and can grow at water potentials well below the minimum for growth of their host plants. Studies on indirect effects of drought on pathogens through other community interactions are still relatively scarce. Positive drought-infection effects can mostly be explained by indirect effects of drought on host physiology. The predisposition and the multiple stress hypotheses are presented, as well as recent developments in the study of the molecular basis of abiotic and biotic stress, and their interactions. Sphaeropsis sapinea on pines, Biscognauxia mediterranea on oaks and root pathogens in declines associated with drought provide illustrative examples, treated as case studies, of pathogens of current significance associated with drought. The conclusion highlights some knowledge gaps, e.g. the role of latent parasites and the shift to a pathogenic stage, or the genetics of some fungal groups. The need for prevention of pathogen dispersal, especially crucial in the case of latent pathogens, is emphasized. drought / water stress / pathogenic fungi / predisposition / forest trees Résumé -Interactions entre sécheresse et agents pathogènes chez les arbres forestiers. Cette revue synthétise les connaissances actuelles sur les interactions entre sécheresse et maladies chez les arbres forestiers, avec trois grandes parties : (1) description des types d'interaction ; (2) connaissances acquises sur les mécanismes impliqués ; (3) trois études de cas bien étudiées. La première partie est basée sur l'analyse d'une base de données d'une centaine d'études, sélectionnées par recherche sur mots clés. La plupart de ces études se rapportent à des maladies favorisées par la sécheresse ou à un effet synergique entre sécheresse et maladie sur l'état sanitaire des arbres, avec une prédominance de m...

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Section: Disease-or Health Status-related Variablesmentioning

confidence: 99%

Interactive effects of drought and pathogens in forest trees

et al. 2006

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“…The number of researchers working on this pathogen in native vegetation had increased from one in 1966 to the equivalent of 15 in 1971 (Newhook and Podger 1972), and a major conference on eucalypt dieback in Australia was held at Lakes Entrance, Victoria in 1973. During the 1970s P. cinnamomi dominated research in forest pathology throughout Australia.…”

Section: Actions By the Western Australian Forests Departmentmentioning

confidence: 99%

“…The reason for these deaths had not been determined, in spite of many investigations into possible causes (Harding 1949;Wallace and Hatch 1953;Stahl and Greaves 1959). Within a few years of Podger's discovery, P. cinnamomi was associated with tree declines and dieback in other areas of Australasia (Weste and Taylor 1971;Marks et al 1972;Newhook and Podger 1972;Pratt and Heather 1973) and around the world (e.g., Kliejunas and Ko 1975;Lübbe and Mostert 1991;Brasier et al 1993;Tainter et al 2000;Balci and Halmschlager 2003). What was not realised was that Podger's data did not support his conclusion about the role of P. cinnamomi in the death of jarrah trees (Davison 2014), although they supported its role in the death of many smaller woody plants.…”

Section: Introductionmentioning

confidence: 99%

How Phytophthora cinnamomi became associated with the death of Eucalyptus marginata – the early investigations into jarrah dieback

Davison

2015

Australasian Plant Pathol.

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The name jarrah dieback was used in the 1940s to describe a serious economic problem in the jarrah forest in the south west of Western Australia. This was the sudden death of groups of jarrah (Eucalyptus marginata) trees that occurred on previously logged sites that had a tendency to become waterlogged in winter. Although the cause was not determined at the time, from symptoms recorded in early investigations the most likely explanation is that the trees died as the result of waterlogging damage. In the 1960s it was shown that many of these sites were infested by the introduced oomycete Phytophthora cinnamomi and tree deaths, together with the deaths of many mid-and under-storey plants, were attributed to this pathogen. A chronology of the research, based on contemporary unpublished documents, shows that in 1968 the conclusion that P. cinnamomi caused jarrah deaths was not supported by the available evidence, because the work did not satisfy the first and fourth of Koch's postulates. The evidence that P. cinnamomi killed many mid-and under-storey plants was much stronger. There are two problems that have been confused: the death of groups of jarrah trees (jarrah dieback) that is caused by waterlogging and the death of many mid-and under-storey plants (Phytophthora dieback) caused by P. cinnamomi infection.

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“…Consequently, damages often occur under wet climatic conditions and poorly drained soils (Sanogo 2006, Xie et al 1999, Rhoades et al 2003, Ma et al 2008. Some of the most devastating Phytophthora diseases occur in periodically wet and dry environments by synergistic interaction between fine root losses by Phytophthora and severe droughts (Jung et al 1996, Balci & Halmschlager 2003, Newhook & Podger 1972. Phytophthora spp.…”

Section: Typical Features Of Phytophthoramentioning

confidence: 99%

“…The introduction of P. cinnamomi to Western Australia in the 1920s (Podger 1972), most likely due to the nursery trade, caused an epidemic dieback of Eucalyptus marginata Donn ex Sm. (Newhook & Podger 1972). As a result of a separate introduction, Eucalypt ecosystems in Victoria are also experiencing dieback caused by P. cinnamomi (Marks & Smith 1991).…”

Section: Typical Features Of Phytophthoramentioning

confidence: 99%

Phytophthora in Finnish nurseries

Rytkönen¹

2011

Diss. For.

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International trade and travel have facilitated the spread of harmful organisms around the world. Human-mediated movement of plants and plant products is now generally accepted to be the primary mode of introduction of pathogens and pests. Species of Phytophthora, a genus of plant pathogens, are commonly spread in this way and have caused severe epidemics in silviculture, horticulture and natural systems all over the world.The objective of the study was to gather information on the occurrence of Phytophthora spp. in Finnish nurseries. Furthermore, the aim was to produce information for risk assessments for these Phytophthora spp. and establish molecular means for their detection. Phytophthora cactorum was found to persist in natural waterbodies and results suggest that irrigation water might be a source of inoculum for the disease in nurseries. In addition to P. cactorum, isolates from ornamental Rhododendron in nurseries yielded three species new to Finland: P. ramorum, P. plurivora and P. pini. The only species with quarantine status, P. ramorum, was able to persist in the nursery in spite of an annual European Commission sanitation protocol. Phytophthora plurivora and the closely related P. pini had more hosts among Nordic tree species and other plants abundant in Finnish nurseries and forest ecosystems. They were also found to have higher infectivity rates compared to P. ramorum and P. cactorum. All four species survived two weeks in -5 °C , and thus soil survival of these Phytophthoras in Finland is likely under current climatic conditions.The most common tree species in Finnish nurseries, Picea abies, was highly susceptible to P. plurivora and P. pini in pathogenicity trials. In a histological examination of P. abies shoot tissues inoculated with P. plurivora zoospores, fast necrotrophic growth was observed in nearly all tissues of the fresh shoot. The production of propagules in P. abies shoot tissue was only weakly indicated.In this study, a PCR-DGGE technique was developed for simultaneous detection and identification of Phytophthora spp. It reliably detected Phytophthora in plant tissues and could discriminate most test species as well as indicate instances of multiple-species infections. It proved to be a useful detection and identification tool either applied alone or in concert with traditional isolation culture techniques. The limitations of the method are also discussed.In conclusion, all of the introduced species of Phytophthora had properties that promote a high risk of establishment and spread in Finland. The efficient transport of Phytophthora via commercial traffic and favorable conditions due to expected climate change will increase the incidence and establishment of Phytophthora in new areas. Thus, it is probable that pathogens of this genus will be introduced and become established in Finland and other Nordic countries unless efficient phytosanitary control becomes standard practice in the international plant trade.Keywords: Phytophthora, pathogenicity, survival, molecular detectio...

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The Role of Phytophthora Cinnamomi in Australian and New Zealand Forests

Cited by 111 publications

References 13 publications

Interactive effects of drought and pathogens in forest trees

Interactive effects of drought and pathogens in forest trees

How Phytophthora cinnamomi became associated with the death of Eucalyptus marginata – the early investigations into jarrah dieback

Phytophthora in Finnish nurseries

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