Resistance to quambalaria shoot blight and myrtle rust in <i>Corymbia calophylla</i> seedlings

Corymbia calophylla (marri), an endemic keystone tree species in southwest Western Australia, is increasingly impacted by the introduced basidiomycete smut Quambalaria pitereka. The rust Austropuccinia psidii (myrtle rust), invasive pathogen recently to Eastern expected spread of Australia eventually. has similar epidemiology Q. pitereka, and there concern that C. may be susceptible. Preliminary pathogenicity tests showed significant differences aggressiveness between twelve pitereka isolates, was evidence interactions isolates provenances. Seedlings from 59 open-pollinated families 11 provenances covering natural range marri were screened for resistance A. under controlled glasshouse conditions. Resistance seedlings within differed significantly. There no correlation psidii. wetter regions more resistant both pathogens, but coefficients insignificant. four three (Serpentine, Chidlow, Kingston) 100% Narrow-sense heritability estimates 0.07 quambalaria shoot blight 0.34 myrtle resistance. results indicate potential use selected families/individuals improvement programs adaptive management strategies.