An estimated 10 million trellis posts per year are used in Australian vineyards and about 75% of these are CCA-treated Pinus radiata. CCA-treated Pinus radiata posts are brittle and at times in short supply. Use of some products containing CCA is being restricted in Australia. Recently, plantation forestry has expanded rapidly for disposal of industrial and irrigation wastewater. Thinnings from these plantations are used as firewood, mulch or simply dumped. Thinnings could be treated and used as vineyard posts. Consequently, our research was conducted to investigate the alternatives to CCA and the suitability of plantation thinnings as vineyard posts. Results have shown a moderate, but not statistically significant, difference in bending strength between CCA and ACQ-treated debarked Pinus radiata posts, in favour of CCA. On average there was no significant difference in bending strength between PEC and ACQ-treated debarked posts of hardwood species (P = 0.54), although two species showed borderline significant differences in favour of ACQ. However, some hardwood species treated with ACQ had more posts rejected due to splitting compared with the same species treated with PEC. No ACQ or CCA-treated Pinus radiata posts were rejected because of splitting.

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