COPPER DEFICIENCY A PROBABLE CAUSE OF STEM DEFORMITY IN FERTILIZED EUCALYPTUS-NITENS

Serious malformation of tree stems and branches was first observed 17 months after planting Eucalyptus nitens (Deane & Maiden) Maiden trees on an improved pasture site in southern Tasmania. The trees were plant ed in a 5(2) factorial fertiliser trial with application of nitrogen a t 0, 60, 120, 240, and 480 kg/ha and phosphorus at 0, 30, 60, 120, and 240 kg/ha. The phosphorus was semibroadcast as a single dose just aft er planting in September 1990 and the nitrogen was applied over a 2-ye ar period from planting. At 21 months of age, the degree of malformati on increased significantly with increasing levels of nitrogen or phosp horus fertilisers and was most severe at the highest levels of applica tion. There was a significant linear trend of decreasing diameter grow th with increasing levels of phosphorus fertiliser. The concentration of Cu in the foliage was significantly lower in malformed than unaffec ted trees whilst other macro- and micro-nutrient foliar levels were wi thin the normal range for healthy individuals. Whilst the symptoms app ear similar to those of ''Toorour syndrome'' previously reported for P inus radiata D. Don on improved pasture sites in Australia, we believe the present symptoms may result from Cu deficiency induced at high fe rtiliser levels. The deformations substantially reduce the merchantabi lity of trees from the plantation.