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Field survey, isolation, identification and pathogenicity of Phytophthora species associated with marri
Louise Croeser is in the final stages of her PhD with the CPSM. She has recently had her first paper published in Forest Pathology. Dieback due to root death and cankers is often caused by Phytophthora, and there are many examples globally. In Western Australia we all know about jarrah dieback, but did you know that marri is also suffering? The obvious symptoms in marri are large bleeding cankers. These are not caused by Phytophthora but by another endemic fungus Quambalaria coyrecup. Because it is unusual for a host to die off due to an infection caused by an endemic pathogen, we suspect that other factors are predisposing the host to this disease by affecting the trees health and vigor. As Phytophthora is often recovered from dying marri roots, experiments were conducted to investigate whether a Phytophthora root infection plays a role (i.e. predisposing) marri to this canker disease.
Soils were collected from cankered and healthy marri, on both disturbed and undisturbed forest stands across the marri range. These soils were tested for the presence of Phytophthora. Five Phytophthora species were recovered, including P. cinnamomi, P. elongata, P. multivora, P. pseudocryptogea and P. versiformis. Disturbed stands had a much higher incidence of Phytophthora than natural forests. Marri seedlings grown in a glasshouse inoculated with these recovered Phytophthora species displayed a reduction in root volume, often resulting in seedling death too. A follow-up study will be conducted, where marri seedlings will be inoculated with both the canker pathogen and Phytophthora, to investigate if Phytophthora was indeed predisposing marri to this canker disease.
>> Read the full paper on Researchgate.
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