The Biology of Phytophthora Cinnamomi in Australasian Forests

Weste, Gretna

doi:10.1146/annurev.py.25.090187.001231

Cited by 148 publications

(97 citation statements)

References 25 publications

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“…In particular, diseases caused by exotic plant pathogens may cause extensive mortality due to the low natural resistance of native host populations to infection and lack of natural enemies (Yang et al 1991;Mack et al 2000;Parker and Gilbert 2004). Chestnut blight, white pine blister rust, and jarrah dieback are well-known diseases that illustrate impacts invasive pathogens can have on natural communities through the loss of dominant tree species (Anagnostakis 1987;Weste and Marks 1987;Tomback and Kendall 2001).…”

Section: Introductionmentioning

confidence: 99%

Impact of sudden oak death on tree mortality in the Big Sur ecoregion of California

et al. 2007

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The Big Sur ecoregion in coastal California is a botanically and ecologically diverse area that has recently experienced substantial mortality of oak (Quercus spp.) and tanoak (Lithocarpus densiflorus) trees due to the emerging forest disease sudden oak death, caused by the invasive pathogen Phytophthora ramorum. In response to the urgent need to examine environmental impacts and create management response strategies, we quantified the impact of P. ramorum invasion on tree mortality across the Big Sur ecoregion using high-resolution aircraft imagery and field data. Using the imagery, we mapped all detectable oak and tanoak trees possibly killed by P. ramorum infection within redwoodtanoak forests and mixed oak woodlands. To validate and improve our remote assessment, we quantified the number, size, and infection status of host trees in 77 field plots (0.25 ha). The field data showed that our remote assessment underestimated mortality due to the occurrence of dead trees in the forest understory. For each forest type, we developed regression models that adjusted our remote assessments of tree mortality in relation to field observations of mortality and local habitat variables. The models significantly improved remote assessment of oak mortality, but relationships were stronger for mixed oak woodlands (r 2 = 0.77) than redwoodtanoak forests (r 2 = 0.66). Using the field data, we also modeled the amount of dead tree basal area (m 2 ) in relation to the density of mapped dead trees in mixed oak woodlands (r 2 = 0.73) and redwoodtanoak forests (r 2 = 0.54). Application of the regression models in a GIS estimated 235,678 standing dead trees in 2005 and 12,650 m 2 of tree basal area removed from the ecoregion, with 63% of mortality occurring in redwood-tanoak forests and 37% in mixed oak woodlands. Integration of the remote assessment with population estimates of host abundance, obtained from an independent network of 175 field plots (0.05 ha each), indicated similar prevalence of mortality in redwood-tanoak forests (20.0%) and mixed oak woodlands (20.5%) at this time. This is the first study to quantify a realistic number of dead trees impacted by P. ramorum over a defined ecological region. Ecosystem impacts of such widespread mortality will likely be significant.

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Section: Introductionmentioning

confidence: 99%

Impact of sudden oak death on tree mortality in the Big Sur ecoregion of California

et al. 2007

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“…Likewise, the Dutch elm disease fungus affects forest structure by changing the amount of standing material and creating canopy gaps that alter microclimate; tree defoliation increases the amount of light reaching the bottom and promotes herb and scrub growth; dead trees contribute to coarse woody debris in streams and decreased availability of nest sites [55,84]. In the same way, the fungus Phytophthora cinnamomi converted large areas of eucalyptus forest to monocot-dominated open savannah, eliminating nest sites and food for many animals [85].…”

Section: (D) Infectious Agents and Ecosystem ( Physical Characteristimentioning

confidence: 99%

Infectious disease agents mediate interaction in food webs and ecosystems

2014

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Infectious agents are part of food webs and ecosystems via the relationship with their host species that, in turn, interact with both hosts and non-hosts. Through these interactions, infectious agents influence food webs in terms of structure, functioning and stability. The present literature shows a broad range of impacts of infectious agents on food webs, and by cataloguing that range, we worked towards defining the various mechanisms and their specific effects. To explore the impact, a direct approach is to study changes in food-web properties with infectious agents as separate species in the web, acting as additional nodes, with links to their host species. An indirect approach concentrates not on adding new nodes and links, but on the ways that infectious agents affect the existing links across host and non-host nodes, by influencing the 'quality' of consumer-resource interaction as it depends on the epidemiological state host involved. Both approaches are natural from an ecological point of view, but the indirect approach may connect more straightforwardly to commonly used tools in infectious disease dynamics.

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“…Disease impact was very high at both sites, with 63 and 29% of the larger and/or common plant species present at sites 1 and 2, respectively, killed by P. cinnamomi. Mating tests (Erwin and Ribeiro 1996) with isolates of known mating type showed that isolates of P. cinnamomi from both sites (n = 10 per site) were A 2 mating type, the common type in Australia (Weste and Marks 1987) and globally (Erwin and Ribeiro 1996).…”

Section: Study Areasmentioning

confidence: 99%

“…In an unreplicated experiment in eucalypt woodland, Weste et al (1973) used trenching and a chemical barrier treatment, combined with fumigation, in an attempt to contain an extensive infestation of P. cinnamomi. The experiment showed promise but ultimately failed (Weste et al 1973;Weste and Marks 1987), probably because of a combination of unfavourable site conditions (soil type and topography), and unusually high rainfall. Hill et al (1995) used physical root barriers and vegetation destruction, combined with chemical treatments (formaldehyde or metalaxyl), in eradication experiments in Banksia woodland.…”

Section: Introductionmentioning

confidence: 99%

Containment and spot eradication of a highly destructive, invasive plant pathogen (Phytophthora cinnamomi) in natural ecosystems

Dunstan

Rudman²,

Shearer³

et al. 2009

Biol Invasions

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The invasive plant pathogen Phytophthora cinnamomi (Stramenopila, Oomycota) has been introduced into 15 of the 25 global biodiversity hotspots, threatening susceptible rare flora and degrading plant communities with severe consequences for fauna. We developed protocols to contain or eradicate P. cinnamomi from spot infestations in threatened ecosystems based on two assumptions: in the absence of living hosts, P. cinnamomi is a weakly competitive saprotroph; and in the ecosystems we treated, the transmission of the pathogen occurs mainly by root-toroot contact. At two P. cinnamomi-infested sites differing in climate and vegetation types, we applied increasingly robust treatments including vegetation (host) destruction, fungicides, fumigation and physical root barriers. P. cinnamomi was not recovered at three assessments of treated plots 6-9 months after treatments. Given the high rates of recovery of P. cinnamomi from untreated infested soil and the sampling frequency, the probability of failing to detect P. cinnamomi in treated soil was \0.0003. The methods described have application in containing large infestations, eradicating small infestations and protecting remnant populations of threatened species.

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The Biology of Phytophthora Cinnamomi in Australasian Forests

Cited by 148 publications

References 25 publications

Impact of sudden oak death on tree mortality in the Big Sur ecoregion of California

Impact of sudden oak death on tree mortality in the Big Sur ecoregion of California

Infectious disease agents mediate interaction in food webs and ecosystems

Containment and spot eradication of a highly destructive, invasive plant pathogen (Phytophthora cinnamomi) in natural ecosystems

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