Chlorosis in plants results from the plant's inability to create the green pigment chlorophyll. The condition can be the result of root congestion, over-watering, high alkalinity, or nutrient deficiency - especially magnesium which is central to the chlorophyll molecule. It's not presenting as iron chlorosis would in Ficus, which would be green leaf veins and the tissue between veins becoming chlorotic. Symptoms are an indication of severe stress.

I am noticing the plant is getting only a small fraction of the light it needs to do well. How have you been fertilizing? with what (include product description and its NPK %s please)? how often? when last? What are you using for a grow medium?

Al

So it's not chlorosis, am I right?

The plant is in a brighter location - I moved it to take that photo.

As I said in the other thread, When I water I always let the water out of the holes (I can't tell you if it's at least 20%) and I never leave the water in the saucers. As you taught me, I tilt the pots to let more water flow out.

I use a liquid fertilizer which here in Italy is the closest to what you use:

I fertilize every 3-4 waterings all year round (even in winter and even in midsummer).

As a growing medium, I use a good quality universal potting soil (Compo universal potting soil). I haven't started growing plants in the two mediums you recommend yet.

I grow all ficuses in the same way and the other ficuses do not have similar symptoms.

It does appear to be a form or chlorosis, but an Fe deficiency is only 1 of many potential causes of chlorosis, and it's not presenting as an Fe deficiency. The new growth on the plant definitely suggests light levels are inadequate. I asked about the grow medium on your other thread, so I'll see what you say there.

I beg a pardon for not paying attention to the fact it was you who posted this thread, which of course made some of my questions redundant.

Al

The new growth on the plant definitely suggests light levels are inadequate.

Very strange. These cuttings have as much light and more than other plants.

Ficus benjamina - full sun:

After defoliating ^^ You can see how tight the internodes are on a plant grown in full sun.

Another:

Also, when you compare the internode length on the newest growth (your plant) to the oldest growth, there is a marked difference.

Al

I just got one more question. In an Italian forum a user hypothesized that it could be a virus (like Aucuba mosaic virus). Do you feel like excluding this hypothesis?

Making a definitive diagnosis of a plant virus is very difficult because it first requires eliminating all other potential pathogens. Often diagnosis depends on finding what look like pieces of the virus and searching for evidence of the unique proteins they synthesize. Since most viruses cause chlorosis in a mottled pattern or ringspot, it can't be ruled out, but it usually takes 3 days or less for a virus to infect the entire organism. Too, infection of nearby potential host plants is easily transmitted by insects with rasping/sucking mouth parts or pruning; so, if you suspect it is a virus, the plant should be destroyed.

Al

I told you I'm that only those cuttings were interested. Actually other cuttings in another pot also have the same problem (first 2 photos). Bboth cuttings back to last summer and were taken from the same mother plant. But there is a third older plant (the next 3 photos) which also has the same problem. In light of this, is the hypothesis that it is a viral infection more probable?

Sorry for not getting back to you sooner. We had a big party here with lots of visitors in town, so for the last several days I've only had a few minutes here and there to check on what's happening at GW.

I don't want to steer you wrong, so I'm not going to be able to help you on this one. Winnowing the list of potential fungal or bacterial inoculates based on symptoms is child's play in comparison to diagnosing viral pathogens, so I have to say I'm sorry, but I'm afraid viruses are beyond the limits of my knowledge.

Al

Do not worry. Anyway, I'll keep you updated, dear Al.