Answer: Based on you description, it is difficult to diagnose your tree's problem. Weeping cherry trees are grafted, meaning an ornamental top is literally attached to a sturdy rootstock; in other words, it is parts of two separate plants attached together. Growth occurring below the graft is from the rootstock, not from the ornamental top.
Occasionally a grafted tree will sucker a little from the root stock, and any sprouts at the base of the tree should be removed regularly before they gain much size at all. (This often happens with crabapple trees.) Occasionally a grafted tree will sprout a few leaves or small twigs from the primary trunk below the graft, and these should also be removed promptly. (If you catch them early you can simply rub them off with your fingers. Otherwise, use a sharp pruner and make a clean cut; current research shows it is best not to use any sealer on any pruning cuts.)
But when a grafted tree sprouts a number of actual branches from the trunk below the graft, it is not a good sign because it indicates that at least some of the energy from the roots is not benefitting the grafted top. There are a number of reasons why this can happen, and you might wish to discuss the branching and possible causes for it with the nursery you purchased the tree from, with your County Extension agent (tel. 489-4315), or with a professional arborist. Good luck with your tree!
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