A survey of CCA (AWPA Type C) treated posts used as grape vine trellis supports, to determine the extent and type of decay was carried out at a terraced vineyard in the Hawkes Bay region of the North Island of New Zealand. Of 357 posts examined out of a total of 970 in the vineyard, 47% had moderate to severe decay or had failed, 20% had established decay, 10% had a trace of decay and 23% had no sign of decay. The posts were less than three years old at the time of the survey and it was predicted that the average life of the posts would be 5 years. Atomic absorption spectroscopy showed that the average above and below ground CCA retention for 13 failed posts were 17.32 and 14.80 kg/m³ of salt respecitively. Light and transmission electron microscopy showed that brown rot was the only cause of decay. The rapid rate of decay was in part attributed to a high inoculum potential for brown rot in the soil caused by the presence of a large volume of decaying wood. It seemed likely that this high inoculum potential conferred a high degree of tolerance to CCA by the brown rot fungus or fungi. Leucogyrophana was consistently isolated from soil but certain observations relating to the morphology of fungal hyphae and the presence of Chlamydospores in decayed wood suggested that another fungus may have been responsible.

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