Today 
Rust is a fungal infection and there are many different types that tend to be specific to particular plants and spreads by means of dust-like spores. The fungus is encouraged by a humid, moist atmosphere and grows on the surface of the leaves and sometimes stems. It takes its nutrition from the plant. This can weaken the plant and in severe cases reduce its flowering or productivity. Bad infestations may result in total loss of leaves and occasionally in death of the plant.
Solution
Organic
Check plants regularly and remove infected leaves by hand. Tidy up any infected fallen leaves to prevent re-infection. This is particularly important in autumn when the spores can overwinter on fallen leaves to contaminate seedlings or new growth in spring. Prune out infected growth and maintain an open centre to shrubs to allow good air circulation through the plant.
Chemical
Spray the plant and the soil around it with a fungicide suitable for the control of rust fungus.
