Properties of reaction zones associated with decay from pruning wounds in plantation-grown Eucalyptus nitens

Decay columns resulting from naturally infected pruning wounds in 5- to 8-year-old plantation-grown Eucalyptus nitens in Tasmania are interfaced by a reaction zone in the sapwood. The reaction zone is blue-purple in colour and occasionally associated with a white zone at the reaction zone/healthy sapwood interface. A log incubation experiment has shown that the reaction zone is particularly durably against decay. The reaction zone is significantly drier than healthy sapwood, with lower levels of potassium, and a lower pH than both sapwood and heartwood. The increased total phenols levels and abundant tyloses in the reaction zone may be particularly important in defence.