Leaves turning black
I just purchased a Prunus campanulata (Taiwan Cherry Blossom Tree) last month and it looks like the leaves are turning black. Some leaves were kind of yellow and brown spotted when I bought it but they said it was because the trees were getting too much sun. The leaves stopped being as yellow but now the top half of this baby trees leaves look like they were halfway eaten (spotty holes/missing half the leaves) and the bottom is fuller leaves but turning blacker like you see in the pic.
Is there something I can do to fix this? Was I mistaken in purchase this tree? I don't know plants well so I took the word of the sales people at Lakos, they're really great and informative. But I plan to buy two more of these and don't want to get bad trees (they're expensive!). Thanks for your advice.