Spot treat with Physan on Den aberrans?

[nzadro]

I got this small Den aberrans from a friend. It has some black spots on the leaves, we were unsure if sun burn or other fungal/bacterial spotting. As a precaution I dusted some freshly ground cinnamon on the leaves. Would spot treating Physan 20 directly with a small brush on the spots help? I only got this yesterday, so unsure if it is actively spreading or not. Is isolation also a good idea? Image attached, note, the spots look greyish due the cinnamon, but I assure you they are black. Thanks.