An impending shortage of naturally durable hardwood electricity pole timbers in Australia has encouraged investigation of alternatives containing less durable, untreatable heartwood. Through-boring or drilling holes perpendicular to the long axis before treatment, has been used successfully on refractory softwood poles in North America and might have application in Australia. The use of through-boring to enhance heartwood treatment was explored in plantation Eucalyptus (E.). Through-boring failed to improve heartwood treatment in E. dunnii and a E. grandis x E. camaldulensis hybrid but did improve preservative penetration in E. globulus and E. nitens. The incidence of fungal decay was also lower in the through-bored zone of the latter two species after 10 years of field testing in Southeast Queensland, Australia. The application of through-boring for improving the performance of these species in roundwood applications such as utility poles merits further investigation.

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