Gummosis blob likely related to failure of top above that point. Multiple possible causes for gummosis on cherries. Perhaps yours has a whopping case of bacterial canker that is attacking the main stem. Native bitter cherry often has large gummosis blobs appear on it here, after which it may die. Sweet cherries also disease-susceptible, yours may be grafted on the top of a sweet cherry trunk.

The blob was actually at the very base of the tree ...about 3 inches above the base, and it stands 6 feet tall. I do not think it is a graft, however.
I removed the blob today. i hope that isn't wrong. It was like a piece of amber...hard as a rock

Yes: I understood what you meant and it does not change anything I said. There could be an infestation or invasion by something near the base of the tree which is causing the entire top above that point to go bad.

Lynn, cherry trees are notorious for getting diseases, of which gummosis is one. Google for it, and you will get more information.

I gather from your first post that you are gardening on a NYC roof top. That, in and of itself, is a stressful environment, and trees in pots are under more stress than trees growing in the ground. That all your other plants and trees seem to be doing well speaks to the excellence of your care. That a cherry tree, no matter how you love it, has come to grief, unfortunately, is not a total surprise. They can do so while growing in the ground, under what SHOULD be the best of circumstances. I think, from what I remember of the prognosis for gummosis, that the tree will continue to decline.

I am sorry to say so, but you will almost certainly have to replace your weeping cherry. I would entirely replace the soil, and maybe put the pot in a different spot on the roof top, if that proves to be the case. I am not trying to be unfeeling, just realistic. And, who knows, I might be wrong.

It isn't in a pot. I have about 1000 square feet of giant metal troughs. I use Sunshine mix ( about 150 3 cu ft bags ful) and laid drip irrigation. I have no "pots" It is a completely similated environment to a meadow. The most sensitive trees are flourishing, so I am confused. The substrate was even sterile when planted, so it must have been systemic within the tree then. The tree is now 3 years old, so having that long of a dormancy is pretty unusual. This stinks! There is no treatment??

ok so I did some reading....but a few things perplex me.
One, there is no "sunken" lesion. The gum made an almost perfectly round blob and dried hard like a rock. I popped it off and it was flat against the trunk with no visible lesion on the tree.
Next, it is very low on the tree, so a borer would come to mind before Psuedomonas would be considered, yet I see no borer hole or disturbance of wood on the trunk. Sooooo confused.

Perhaps I should have said "container", rather than "pot". Either word, your tree is growing on a NYC roof, and not in an actual meadow. That you are able to keep other, putatively more sensitive, trees thriving is great. As you may have gathered from the number of recent posts about cherry trees, weeping or otherwise, many people have difficulties with them.

It may be that something damaged the bark, and sap wept out and solidified, and there is no disease involved. It is possible that your tree acquired a borer - does it look like the sap solidified from a small hole? It is possible that your tree does not have gummosis - all you can do at this point is wait and see. Keep an eye on it, and if there looks to be something else wrong, then post again.

That the soil was sterile when you planted implies that if your tree has gummosis, then it came from the nursery - I don't know the incubation period well enough to say for sure. But, I am sure your trees are visited by birds and insects, so one of them could also have brought some disease in on feet, feathers or through droppings.

Thanks dibbit. I guess I will hope for the best. My neighbor has one as well that looked like crapola last year...e.ven lost all of its leaves, but this year after the bloom, it flourished and is fill and green, and she has hers in 1/5 the size of the trough :( I will hope for the best and if it dies, replace it with an undulating birch maybe. Thanks again.