Puccinia malvacearum (Hollyhock rust)

Puccinia malvacearum is one of a number of rust fungi in the genus Puccinia that have been reported from the genus Malva (see Demers etal. 2015, Farr & Rossman 2017). Worldwide, Puccinia malvacearum is known from 100 host plants including several native Australian plants (Farr and Rossman 2017) and from what I can see is the only rust species reported from Malva parviflora in Australia. I get Malva parviflora growing as weeds in the garden and they often get this rust in a wet spring/summer. Normally I like to see some microscopic details of spores to be able to distinguish rust species, but in this case this is something I’m familiar with and your image accords with what I’ve seen for this species. It is possibly the only pathogen reported for Malva parviflora in Australia, unfortunately the Australian Plant Disease Database is not accessible to the public so I can’t search it. References: Demers J.E., Romberg M.K., Castlebury L.A. (2015) Microcyclic rusts of hollyhock (Alcea rosea) IMA FUNGUS · 6(2): 477–482. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4681263/pdf/ima-6-2-477.pdf
Farr D.F., & Rossman A.Y. (2017) Fungal Databases, U.S. National Fungus Collections, ARS, USDA. https://nt.ars-grin.gov/fungaldatabases/fungushost/fungushost.cfm