Mango seedling leaf's mosaic pattern - if it is a cause for concern or not?

[Fender1990]

At the time I am trying to understand if mosaic leaf pattern in my young mango seedling is a symptom or not but can't find something similar in appearance.

My young mango plant now is 4 months old. It is Kent variety which grew up from a seed of store bought fruit in a pot indoors. At the planting time seed was remarkable for black mold lesions. It was planted in peat (pH 5,5 - 6,5) plus a bit of perlite mix, grew in room temperature (23 - 25 C), with 3 - 4 hours of direct sunlight per day and had approximately 1 watering per 7 to 8 days (to the point when the soil dried up to 5 cm from above) and firstly the things went just ok and it was fine. After a three months or so one day I surprisingly discovered, that older leaves look a bit of mosaic through the light but otherwise plant was good. Later I found out that underside of the leaves covered with some sticky stuff along the veins, which was removed with water and soft cloth and today, which is a week o so later, I saw small (2 - 3 mm) black spots on the oldest leave with increasing of that patchy mosaic pattern. It's underside was covered with similar sticky substance and more over, at the first time there was aphids - as well as on the underside of the other leaves, stem and potting soil surface.

The leave was removed because of the black spot disease (I'm not sure if it is anthracnose, but afraid of it), all the leaves was washed and rubbed a bit with water and soft cloth once again till I couldn't find any sticky aphid's stuff underneath and azoxistrobin (1 ml of 250 g/l suspension per 1 l of water) was used because of some fungal infection concern. But after all, mosaic looking leaves remain, so now there are some questions. 1) Is it some sap sucking insects the cause and some treatment required (at first, probably, soap+oil+water or something else)? 2) Is it any systemic fungal infection and some systemic fungicide needed? 3) Is it some nutritional deficiency because of peat? 4) or is it just something unrelated (which is obviously the less likely) to other problems?

Need to say, that in that seedling some stem luxation appeared progressively, so I'm concerned about some fungal root rot or something like that. But for now it looks quite good.

Thanks a lot!

 

[Chuck]

You did not mention what your are feeding your plant with. Peat has zero nutritional value for plants. If the pictures are accurate the bottom of the leaves are not supposed to be yellow. They should be of the same shade of green as the tops of the leaves only lighter in color. As far as the mosaic is concerned, IMO, it is old insect damage caused by aphids or other sucking insects. Where the insects penetrated the leaf's epidermis and into the cuticle it caused damage to the cuticle thus impairing photosynthesis and thus the yellowing.

 

[Fender1990]

No fertilizer was used, so after couple of months of slow growth some nutritional deficiency came to mind also. Leave's upperside has almost the same colour as an underside with no yellow areas. This mosaic "circles" actually some sort of light green color even through the light also and translucent. So, long lasting aphid infestation as a cause of all other problems looks quite considerable. Shall I start to apply some anti-aphid stuff already or just wait for the previous "wash and rub" effect?

 

[Chuck]

No fertilizer was used, so after couple of months of slow growth some nutritional deficiency came to mind also. Leave's upperside has almost the same colour as an underside with no yellow areas. This mosaic "circles" actually some sort of light green color even through the light also and translucent. So, long lasting aphid infestation as a cause of all other problems looks quite considerable. Shall I start to apply some anti-aphid stuff already or just wait for the previous "wash and rub" effect?

Mango trees and mango seedlings are HEAVY feeders. If you haven't fertilized them it is only a matter of time until you see major unknown problems. The aphid damage may be visible because of this. The seedling MUST be fed or it will become a magnet for damaging insects, bacterial, fungal and viral infections. I am surprised it hasn't already. It REQUIRES a steady diet. It should also be repotted into something other than pure peat moss and perlite.

 

[Fender1990]

So what to do first then? Shall I feed it first and then wait for aphid damage symptoms to disappear/reduce and after that transplant in some regular potting soil for example? Does osmocote to be a choise in that case?

 

[Chuck]

So what to do first then? Shall I feed it first and then wait for aphid damage symptoms to disappear/reduce and after that transplant in some regular potting soil for example? Does osmocote to be a choise in that case?

Repot. Osmocote is about as good a synthetic fertilizer as you can get. Mix the osmocote into the potting soil and put some on the surface. The plant does not, at this time, show signs of trace mineral deficiencies so no need for soil amendments but keep close eye on further yellowing, color change, abnormal growth etc.

 

[Fender1990]

Repot. Osmocote is about as good a synthetic fertilizer as you can get. Mix the osmocote into the potting soil and put some on the surface. The plant does not, at this time, show signs of trace mineral deficiencies so no need for soil amendments but keep close eye on further yellowing, color change, abnormal growth etc.

Ok, I'll definitely start with it. Thank you for advise.