In a pot or the ground?

You live in zone 7 -- but where?

One guess: Possible root problem. Have to sort through the myriads of possibilities including cultural -- as in too dry or too wet..

Let's start by you posting and image of the entire plant.

jean,
I grow in 3~4 gallon pots since it's too cold outside in winter here in Seattle. One's in a ceramic pot and the other in a plastic pot if that matters. Both have drainage holes and are filled with 3 parts peat moss 2 parts topsoil. They did fine for several months, but the leaf problem is consistent with one of the trees now. It is essentially defoliated except for the new growth at the top. Here is an older thread I had when the problems weren't so severe, but the symptoms were slightly different in that it was turning red and not drying up. .

Here is a link that might be useful: Miracle Fruit Plant Leaf Problems

The problem is not a disease.
The problem is low functioning roots.
The reason is that peat moss and top soil *don't drain well* in a container. You must use a mix that is specifically formulated for container growing.

One person in the other thread mentioned 1:1 perlite and peat works.

Or you could try an "acid mix" for containers such as one to use for azaleas and camellias. If you want it to be less moisture retentive, add some perlite.

You didn't make any comment re temperature. In one site, it was said 65F is a minimum but higher is better.

One link below.

Another is this:
http://www.gardeningknowhow.com/houseplants/miracle-berry/miracle-fruit-plant.htm

Here is a link that might be useful: how to grow it - from CA Rare Fruit Growers (CRFG).

Sorry to resurrect an old thread, but I am having the exact problem with
my miracle berry plant. Did yours ever recover and what did you do?

I also wonder if your plant recovered.

I have a very similar-looking problem with my miracle berry bush; it also has no new viable buds or new leaves.

I've acidified the previously alkaline soil with dilute acetic acid, apparently without benefit.

...Presuming it suffers from a root problem, I'm going to try re-potting it with better drainage and some peat and perlite.