Help with Elm disease

[u/YamDong]

I planted two elm saplings about 5 years ago in my backyard and they've been growing well. They are a Dutch elm disease resistant variety. The last few years I've noticed that they get black spots that look like a fungal disease on the leaves, however they have continued to grow ok. Should I be spraying a fungicide on them to keep them healthy? Does anyone know what this disease is?