I live in central North Carolina. We planted about 20 of these last fall to grow as a screen b/t us & our neighbors. Mid to late summer, I noticed this happening on a lot of the new growth leaves. I thought it might be a fungus & sprayed Neem oil every week or two for probably two months but it just seemed to spread further. I fertilized them with Bayer Rose fertilizer (liquid) 3 times from spring to early fall.
I just went out & trimmed off all affected leaves hoping to rid them of whatever is going on before new growth starts. Does anyone know what is going on & how I can stop it? I've attached photos. Any help is greatly appreciated.