In this case, fungicide will be helpful. But you need to improve the health of the damaged plant, so it’s better to combine using fungicides with additional tree care. And this also will guarantee that the disease will be less likely to appear again.
Pruning of the three is also a good idea. Pruning helps to establish proper air circulation, which makes the tree healthier. And during this process, you will cut the affected leaves or branches, which also minimizes the chances of diseases reappearing.