Question
My daughter purchased a weeping cherry tree and the day after we planted it, holes began appearing on the leaves. The are new leaves sprouting, but that are also getting holes in them

Answer
Several insects will do this--caterpillars, Japanese beetles etc. I would treat the tree with a systemic insecticide called Bayer Advanced Tree and Shrub Insect control. This is applied to the soil around the tree and the tree  roots will transport it to the leaves and twigs. When the insects feeds on the leaves they will be killed. This protection will last the whole season. Here is a web link to this product. Check with your local nursery fro this product.  

http://www.bayeradvanced.com/product/Tree-Shrub-Insect-Control/concentrate.html