Question
Planted a weeping cherry about a month ago, now I notice holes on the leaf what type insect or disease does the tree have and how can I combat it.

Answer
It might not be an insect.  There are fungal diseases that cause the "shot-hole" effect on leaves.  There is not too many ways to tell the difference.  If you want to treat for insects, buy Bayer Advanced Tree ans Shrub Insecticide from Home Depot.  This product is mixed with water and poured on the soil around the base of the tree.  It is taken up systemically and will kill any bugs within a week or so.  It also provides protection from reinfestation for up to a year.  Try this first and see if there is improvement.  If not, respond back and we will chase down the fungal disease option and see if we can treat that.  Thanks.