Rust spots on your leaves
There are fungi that can attack your fig tree leaves. If you find large brown areas, or with a mold growing – immediately cut off the affected leaves and discard them so that the fungus will not spread throughout. Take note that there is a very dangerous common leaf mold pathogen called Rust. It mainly affects potted plants and can spread to your house plants. It will begin with small brown spots and gradually spread through the leaf. When you discover this type of infection, cut the leaf off and burn it.
This fungus generally appears following long rainy days without a chance for the leaves to dry under the sunshine. If you touch an infected leaf, be sure to wash your hands thoroughly before handling other plants. Sometimes if you see sporadic brown spots, on a few leaves don’t be alarmed. Rust will not kill your tree and you don’t have to remove all of the leaves. It’s best to monitor the brown spots carefully to assess the situation before of jumping to conclusions. Sometimes small brown spots can indicate that the plant suffered from lack of water following a yellowing of the leaves.
There are anti-fungal products available, though the most effective means of stopping the spread of this infection is by burning the leaf. I use a small propane torch with the leaf on a non-flammable surface while the leaf is still green.