Macruropyxis fulva is a newly described rust pathogen causing tawny rust of sugarcane in southern Africa. It has been observed on a number of commercial South African varieties grown under varying environmental conditions. Macruropyxis fulva is the third rust pathogen, together with Puccinia melanocephala (brown rust) and Puccinia kuehnii (orange rust) known to infect this crop. A touchdown PCR assay specific for M. fulva was developed to rapidly and reliably differentiate this new rust from the other two rusts infecting sugarcane.