Answer: Your 4 in 1 cherry tree has four different varieties of cherries grafted onto the tree. It sounds as though one of the grafted branches died. This sometimes happens and the best thing to do is to cut it off the tree. Now you probably have only 3 different cherries on your tree. There's not much you can do to keep the grafts from dying out - it just happens. To keep your tree as healthy as possible, make sure it gets plenty of sunshine and than you water it deeply once or twice a week.
Best wishes with your tree!
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