Rust is normally a problem in the high humidity and heat of summer as it favours that sort of weather but winter has been very mild and humidity is already high. Rust is a fungal condition which is identified by yellow or pale green spots developing on leaves, stems and flower stalks followed by the development of orange spores. There are many species of rust with different species affecting different plants. Leaf moisture is required for spores to germinate and infect the plant. Spores from infected plants are spread by wind or direct contamination from one plant to another. Many people here are familiar with rust on frangipani leaves.
Rust can be treated with appropriate fungicides, available from Tanby Garden Centre, but care should always be taken when disposing of infected leaves and plants as the rust spores are easily spread. Avoid watering leaves on susceptible plants and instead water only at the base of the plant.
eco-fungicide is an organic fungicide that is safe for the beneficial insects in your garden and safe for soil microbes and earth worms. It works by altering the pH of the leaf surface inhibiting the germination of new fungal spores and also by attacking the cell walls of existing fungal infections causing dehydration and death of the fungal growth. Thus there is a preventative and curative action.
Remember that healthy plants deal with the stresses of pests and diseases much better than weak plants. Look after your soil and have plenty of diversity in your garden.
Sources: NSW Dept of Primary Industries Pests, Diseases, Disorders and Beneficials in Ornamentals: Field Identification Guide; The Garden Guardians by Jane Davenport.