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A new Phytophthora species associated with Eucalyptus gomphocephala decline in Western Australia

Scott, P.M., Shearer, B.L., Barber, P.A., Jung, T., Burgess, T., Colquhoun, I.J. and Hardy, G.E.St.J. (2008) A new Phytophthora species associated with Eucalyptus gomphocephala decline in Western Australia. In: ICPP 2008 9th International Congress of Plant Pathology, 24 - 29 August, Torino, Italy,.

Abstract

Eucalyptus gomphocephala is a keystone tree species endemic to a narrow (5-10 km wide) coastal strip approximately 300 km in length in south-west Western Australia. E. gomphocephala is undergoing a significant decline that was first identified as a spot decline in 1994 and now occurs throughout large sections of its remnant distribution within Yalgorup National Park in the southwest of Western Australia, in some areas resulting in 100% mortality. Multiple factors, including soil-borne plant pathogens, have been identified as possibly contributing to the decline syndrome. Less fine roots are associated with trees on decline sites compared to those on healthy sites. Foliar analysis indicates that declining trees have lower concentrations of some micronutrients, including zinc, the uptake of which is typically impaired by fine feeder root loss. A range of Pythiaceous microorganisms have been isolated from declining roots, including an isolation of a yet to be described Phytophthora species. The Phytophthora isolates appear morphologically similar to the Phytophthora citricola holotype although they are distinct from this based on molecular analysis of the internal transcribed region. The exact phylogeny of the new Phytophthora species is being determined using additional gene regions including the amplification of mitochondrially encoding Cox I and II spacer regions. These isolates appear to be contributing to the loss of fine roots. Glasshouse trials are currently underway to determine whether these isolates are indeed pathogenic.

Publication Type: Conference Item
Murdoch Affiliation: Centre for Phytophthora Science and Management
URI: http://researchrepository.murdoch.edu.au/id/eprint/3260
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