Phytopathology (1996) 86, p. S102 (O'Gara et al.)

E. O'Gara, G.E. St. J. Hardy and J.A. McComb (1996)
Infection of Eucalyptus marginata by Phytophthora cinnamomi: The role of collar infection
Phytopathology 86 (11 suppl.), S102-S102
Abstract: Approximately 14% of the E. marginata (jarrah) forest of Western Australia is infested with P. cinnamomi, Bauxite mining is carried out in the jarrah forest. P. cinnamomi can kill up to 38% of jarrah plants on rehabilitated mines. Deaths of seedling jarrah in rehabilitated mines were frequently observed where ponding of rainwater had occurred around the plant collars and P. cinnamomi was often isolated from the collar but not the roots of the dead and dying seedling. A glasshouse trial was conducted to determine if it is possible for P. cinnamomi to infect the collar of jarrah through the periderm and if wounding is necessary for infection to occur. A watertight cup was constructed around the collar of each experimental tree to simulate localized ponding. The wounded and unwounded plants were exposed to the pathogen by filling the cups with P. cinnamomi laden water. The results showed that zoospores of P. cinnamomi could successfully penetrate and infect both unwounded and wounded periderm at the collar of E. marginata. Successful infection resulted from inoculation with both zoospores and mycelium of P. cinnamomi. Lesions resulting from inoculation of wounded plants with motile zoospores were significantly longer than those resulting from inoculated unwounded plants.

Research topic(s) for pests/diseases/weeds:
general biology - morphology - evolution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Phytophthora cinnamomi	Eucalypt (Eucalyptus)