The image seems to show a gall that resembles those associated with the rust Uromycladium. The problem is that the host is given as a dead gum sapling. Literature records show only plants in the Fabaceae as hosts to species of Uromycladium and in Australia that seems to be Acacia species and Paraserianthes lophantha only. Overseas Uromycladium is known from these genera Acacia, Falcataria, Paraserianthes and Racosperma. A very recent paper has described 16 new species of Uromycladium see Doungsa-ard,C. et al. 2018. Diversity of gall-forming rusts (Uromycladium, Pucciniales) on Acacia in Australia. Persoonia 40, 2018: 221– 238. From http://www.repository.naturalis.nl/document/656940
Dear Ken, thanks very much. I had another look at the dead sapling and it is quite likely to have been a wattle. It has been dead quite a while. Sorry for the confusion. Jacky