Woodlands Historic Park Galls

rust galls on Hedge Wattle stem at Woodlands Historic Park
galls on Hedge Wattle, caused by a rust fungus

The fungus which causes these galls is called Uromycladium paradoxae. It was previously known as Uromycladium tepperianum which was the species considered to be responsible for galls on over 100 species of Acacia (Morris 1987). Uromycladium tepperianum has now been separated into at least 16 species (Doungsa-ard et. al. 2018).

The galls can form on stems, branches, phyllodes and flower buds. They are very common on Hedge Wattle at Woodlands Historic Park, with some plants having many galls up to 40mm across.

Rust galls can provide food and habitat for many species of insect. A study of galls on Lightwood Wattle in NSW, caused by what was then considered a strain of Uromycladium tepperianum, found larva of 16 species of moth inhabiting them (Hosking et. al. 2010). In Tasmania a study of Uromycladium tepperianum galls on Silver Wattle (Bashford 2002) found not only 9 moth species but also adults or larva of 15 species of beetle in or on the galls. Furthermore, seven species of wasp and one species of fly were found to have parasitized the moth and/or beetle larva, making a total of 32 insect species benefiting from the galls.

The galls on Hedge Wattle do not grow as large as those on the larger species of Acacia in those studies, and they do not live as long either. There has not been any study of the insect diversity they might support.