Question
We are in spring, the blossoms are gone, the tree is full of leaves. I have rechecked the tree I do see small tufts of leaves coming through all over the tree but not at the tip of the branches. There is no white or gray substance on the underside of the fallen leaves. When you stand back and look at the tree you see about 3/4 of the leaves on the tree curling up. You don't notice any leaves on the ground until you look very close.  It is a gradual process of the leaf curling, going brown around the edges then dropping, and new leaves growing until autumn comes. We have made up a fungal spray and poured it into the ground around the tree, then sprayed the tree.  
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Our weeping cherry blossom tree blossoms then gets leaves then the some of theleaves start to curl get brown around the outside then disappear, by the middle of summer there are branches that have few leaves, new one keep growing but the tree is struggling to keep up, what can we do? we have used fungal spray.
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Hi Marlene,

First.  Can you answer a few questions for me?  Do you see small tufts of leaves at the tips of the branches after the affected leaves have dropped?  Have you also seen any white or gray substance on the underside of the fallen leaves?  These are symptoms and signs of a fungal disease, Withes' Broom, caused by _Taphrina cerasi_.  

This fungus infests both stem and leaf tissues, so control measures must rid the plant of those sources of fungal spores.  The preferred method of treatment is to prune the infested branches approximately 12 inches below the point of visible infestation, i.e. where the leaves have shown deformities and defoliation has taken place.

Of course at this time of year in northern latitudes, the trees are probably defoliated, so the affected branches may not be as visible.  The first thing to do is to clean up any fallen leaves and twigs from beneath the tree and burn them.  Next spring as the symptoms become apparent, prune out those affected branches and also burn those trimmings.  

This disease affects entire branches and spreads by fungal spores to adjacent branches.  The pruning may give your tree an unusual appearance for a while.

Answer
Hi again Marlene,

Thanks for the additional information.  (I envy you; it is autumn here, and we are facing winter.) If this is Witches' Broom, the tuft of leaves will appear later in the season at the tops of the branches after the disease progresses.  This is not the right time of year to see the "witches' broom".  The new, emerging leaves are inoculated with the fungal spores as they emerge from the already-infested stem.

There are many environmental factors that can cause leaf deformities and discoloration that you describe.  Application of fungicides (according to manufacturer's instructions) can be effective as a way to minimize the fungal diseases.  From your description, though, there are only general symptoms which may be either biological or environmental related.  Signs (fungal mycelium, etc.) are not yet visible, and may be identifiable only microscopically by a trained plant pathologist.  (Some Universities have extension services that can help identify plant pathogens.)  

Over the next several weeks take observations on the leaves that show symptoms (plant-related) or signs (pathogen-related): the presence of spots four to six weeks after flower petals fall. Spots may be only pinpoint in size. During wet, humid periods, examine the underside of leaves to determine if masses of whitish-pink conidia (fungal spores) are beginning to form.  These are indications of fungal diseases.  If you see those, seek the assistance of a local arborist or plant pathologist for correct identification and treatment.

Sorry, I couldn't be more helpful.

Good Luck!