Fungal galls

@KenT I believe it is implexa. See Acacia implexa (Hickory Wattle, Lightwood)

The foliage looks like that of Acacia implexa if that is correct then the stem gall is that of the fungal pathogen Uromycladium implexae as currently the only species of Uromycladium known from this host.

Thanks Ken. I should keep to bugs I understand :-)

This is one of the Acacia gall rusts. The host looks like it might be Acacia dealbata, if so, then both Endoraecium carnegiei and Uromycladium murphyi are known from this host. To distinguish between the genera requires using a compound microscope.

I would expect this to be Uromycladium murphyi, thus far it is the only known gall rust on Acacia decurrens based on the following paper Doungsa-ard, C.; McTaggart, A.R.; Geering, A.D.W.; Shivas, R.G. (2018) Diversity of gall-forming rusts (Uromycladium, Pucciniales) on Acacia in Australia, Persoonia Volume 40, June 2018, pp. 221-238. No species of Endoraecium are presently known from Acacia decurrens relevant reference is A.R. McTaggart, C. Doungsa-ard, A.D.W. Geering, M.C. Aime, R.G. Shivas (2015) A co-evolutionary relationship exists between Endoraecium (Pucciniales) and its Acacia hosts in Australia. Persoonia 35: 50–62.