First you should try and determine what is killing the tree. Perhaps a fungus,
or
some systemic problem. You could trim off the dead and weak branches leaving
the single live one and hope the tree will recover. If it does, the existing
root structure should push a lot of new growth next spring. If the tree was
grafted and
you suspect the rootstock as the problem, you can try grafting some scion twigs
from the live branch onto a new rootstock. Dig around the base of the tree to
check
for rot or insect damage. You may take a leaf from one of the dead branches
into
your local extension office for analysis. I assume you gave it the normal care
this year with watering with this unusually hot summer.

Sherwin D.

Victor Ervine wrote:

I have a plum tree planted 3 years ago, this year almost all the leaves
died early only one small branch still appears to be alive the tree had
no fruit on it this year. What can I do to save it as it appears to me
to be dying.

--
Victor Ervine