Bonsai ginseng

Question: Bonsai ginseng

I have had a ginseng bonsai for two years. It is positioned in the room facing the south-facing window.
lately I have noticed that the leaves have become opaque as if they had a white patina on them and many turn yellow and then fall off. what could be the problem ? I take it regularly once a week, checking that the soil is dry before giving it water. I recently added universal soil and I notice that it is very permeable thanks a lot!

Answer: Bonsai ginseng

Dear Simona,
not seeing photos of the plant it is difficult for me to understand the concept of white patina on the leaves; since the plant is not well, and the leaves fall, I think it has been attacked by some parasite, fungal or animal. The most common parasite that causes a white patina is hatred, also called white mal, but this fungus preferably develops in the garden, in spring, especially in particularly humid periods, with low temperatures. Unless in your house there are less than 12 ° C and high humidity, I doubt that it could be oidium, as this fungus develops on the leaf pages that remain moist for a long time.
Since you water your ficus correctly, you keep it in the correct lighting conditions, and for everything else you seem to have a really green thumb, I think your plant is suffering due to adverse climatic conditions.
Probably the leaves that dry and the white patina are due to the presence of mites, which often develop in the apartment, due to the excessively dry climate.
Often these insects are particularly devious, as they are very difficult to see with the naked eye, and therefore it is not easy to understand that the symptoms manifested by the plant are to be attributed to a small spider that is not seen.
To eliminate mites, many insecticides are not effective, as mites are not insects but arachnids, or small spiders; for this reason it is necessary to use special acaricides to eradicate them; insecticides are often also acaricides, and therefore kill both spiders and insects; in your case, if you can find a systemic acaricide at the garden center, it would be the ideal product, because instead of spraying it on the leaves you will have to use it dissolved in the water of the first watering, and therefore you do not risk spreading it throughout your home.
In general, the mites develop in very dry climates, so they are unwanted and undisturbed hosts of the rock garden in August, of the greenhouse, and even of the apartments, where the air is decidedly dry, as the heating system strongly dries the air.
To prevent your ficus from suffering due to dry air, sometimes in winter remember to spray the hair with demineralized water.