Field survival and growth of clonal, micropropagated Eucalyptus marginata selected for resistance to Phytophthora cinnamomi

Clones of jarrah (Eucalyptus marginata), micropropagated from glasshouse-grown seedlings selected for resistance or susceptibility to Phytophthora cinnamomi, were planted in a former bauxite mine-site in the jarrah forest and inoculated with P. cinnamomi. Mortality after 13 years in resistant clones was 0–30%, while that of susceptible clones was 40–100%. Mean heights of resistant clones after 13 years were 7.8–13.6 m, while heights of surviving susceptible clones were 0.9–6.7 m. The resistance character of the seedling ortets was transmitted consistently to the clones. The field mortality of clones of some rare, apparently resistant seedlings selected from susceptible half-sib families was low after 1 year, but approached that of the susceptible clones after 2 years. The results show that Phytophthora-resistant jarrah ortets can be selected using stem-inoculation of glasshouse-grown seedlings; the resistance of the resulting clones has been validated in the field in an inoculation trial.