Copper spray doesn't take away the rust, it prevents it from spreading further. The best way to treat rust is to remove all leaves that have ANY sign of rust and spray the tree with copper spray to prevent it from coming back.

Joe

How does the rust on the leaves look like?

foolishleasure it looks like brown speckling over the entire leaf.

Joe... is it necessary to repeat the treatment? If so at what interval? I did spray the trees twice after pulling off the affected leaves but it is still present/ spread to other new growth. But the new spring growth may be ok so far.
Thanks

foolishpleasure here is a picture of fig rust

From what I understand rust is a fungus and spreads by spores. The copper spray affects the spores so that they do not develop into the fungus. It does not affect the fungus itself, which is why you have to manually pull those leaves. I grew figs in Massachusetts for several years and rust was the biggest problem I faced there with all the rainy, cool weather. I learned that to really control the rust you have to be merciless and pull every leaf that has any sign of rust. Periodic spraying of the copper spray is necessary to prevent any spores that are present from developing into the rust, especially when weather conditions promote the growth of fungus.

Joe