Copper-chrom-arsenate treated softwood posts used as trellis support structures in 5 major horticultural districts of New Zealand were systematically examined for presence of decay. Principal crops on properties examined were grapes and kiwifruit; a minority of properties grew hops, boysenberries, and dwarf apples. Occurrence and severity of decay were variable within specific age classes of posts on individual properties and also between properties in the same region which had posts of similar age. Incidence of decay was higher in posts set in soils which were highly moisture retentive than in posts in drier areas or set in freely draining soils. Cross-sectional size and age of posts showed little correlation with frequency of severe decay, although the percentage of posts free of decay increased with decreasing age.

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