Very difficult to identify a problem from the photograph. Could possibly be powdery mildew, a serious spider mite infestation, or improper watering. Is the whole volume of potting medium getting a good soak on watering day, or are you delivering little sips?

Solanum pseudocapsicum is quite toxic to animals and youngsters, so be sure to get all of the fallen fruit. I mention this only as a precaution...in case you don't already know. :-)

In addition to Dori's questions ...... did you fertilize it? Where do you live?

Al

rhizo_1
I just water it until the water drain from the bottom
thanks to you I know it is toxic I read too much about plants , but I don't know why this problem occurs with it

Tapla
I live in Iraq , the green houses here don't let the plants too much care and there is no good fertilizer .I use spray instead of fertilizer .

sorry for my bad English

I think that your English is great!

thank you I really hope this

And what kind of 'spray' do you use? What is in it?

Al

There is no ingredient written on the spray bottle just cautions in different languages

this is the spray I use

That spray appears to be leaf shine, not a fertiliser. If you can buy leaf shine I would have thought you could find some house plant food. Baby Bio is the most common in the UK.

That said I don't think your plant's problems are caused by lack of fertiliser. It looks as if it is mildewy and shows signs of being kept too warm, too moist and too dark. I don't know what your outside temperatures would be at the moment but it could probably take some time out in the fresh air. Winter Cherries tend to be short lived indoors but I have seen them thriving as low shrubs in gardens in Italy. Just before Christmas I saw one in a snowy garden near Milan.

Saleh - the reason I'm asking about fertilizers and anything you might have sprayed on the plant is, I'm getting the sense that this might not be related to a disease like PM. Rather, it looks to me as though it might be a negative reaction to either a chemical compound or the vehicle (what the chemical is dissolved in) used to deliver it.

Al