Rust fungi, some of the most economically and environmentally important plant pathogens, are amenable to double-stranded RNA (dsRNA) mediated control. However, to date, dsRNA treatments have only been applied prior to infection. In this paper, we show that a dsRNA spray can effectively prevent and cure infection by Austropuccinia psidii (cause of myrtle rust) at different stages of the disease cycle. We found that dsRNA, applied preventatively or curatively, inhibits myrtle rust disease and improves plant growth and recovery following severe infections. These findings have immediate potential in the management of the more than 10-year epidemic of myrtle rust.