If you are not seeing much leaf spot then I wouldn't be concerned at this time. Mulberries and figs do just fine with slight infestations. I sprayed with a fungicide (and am still spraying) just to see if this is what it would take to keep a Morus nigra alive and growing well in the Southeast. All of the old growth is covered in fungal leaf spot, and I don't want the new growth that is pushing out now to get infested. Besides, I don't really know if this is the main culprit in the southeast, and if the plant still dies after continuous fungal treatment, I will know there are other issues to decipher.