Seedling stem issue

[TestoTarzan]

Hi
See attached pictures. Many of my seedlings get this white crown around the stem, and a white powdery crust forms on top of the soil. In some cases the white stuff seem to be eating away at the stem, causing the bark to flake off. I keep them in my greenhouse. For some I use my own homemade bonsai soil, and some are kept in plain garden soil with perlite. Some people suggest it is the water that I use that is causing the problem, some people say it's the soil, some people say it is a mold issue. At this point I have no idea what to think anymore. Can anyone tell me the reason why this is happening? And if possible, what can be done?

 

[penumbra]

I suspect it is calcium in your water. I lot of us have to deal with this.

 

[TestoTarzan]

I suspect it is calcium in your water. I lot of us have to deal with this

I practice the same watering routines on all my trees. If the problem is calcium heavy water, wouldn't all my trees be affected the same way?

 

[Wires_Guy_wires]

I practice the same watering routines on all my trees. If the problem is calcium heavy water, wouldn't all my trees be affected the same way?

No.
Peeling pine bark is dead tissue and it'll act like a wick, drawing water upwards where it evaporates and leaves a white dust behind from the salts.
Salts attract more water, more water is drawn, more salts build up.

Not all plants have peeling bark that acts like a wick.

 

[TestoTarzan]

No.
Peeling pine bark is dead tissue and it'll act like a wick, drawing water upwards where it evaporates and leaves a white dust behind from the salts.
Salts attract more water, more water is drawn, more salts build up.

Not all plants have peeling bark that acts like a wick.

Okay, I understand. So what do I do to reverse the effects? Obviously I should start collecting rainwater instead, but what else can I do?

 

[Wires_Guy_wires]

There's not much else you can do, since it's just a characteristic trait of how your plants work.
Once they develop real bark, it'll become less of an issue. When there's moss growing, it'll be less of an issue too.
Aesthetically, seedlings are ugly.

Maybe you can rub some olive oil on the trunk, make it more water repellant. But that only works for a while.

At some point your soil will evaporate better, and it will mitigate the issue even further.

What I'm saying is that there's not much you can do on the long term to stop or prevent this from happening. Even rain water will take up nutrient salts and form a salt layer. It's best to just accept that it happens to all of us, I believe.

 

[Shibui]

It is not entirely clear from the photos but this is more usually a mineral build up. Being in the glass house often makes it worse because it's warmer so more evaporation from the soil surface. Misting or light watering makes it worse. Heavier watering may flush out the mineral rich water left after evaporation.

Should be easy enough to decide if it's mineral or fungal. Mineral is hard and crusty and can be difficult to rub off whatever it is forming on. Fungal is soft and should rub off relatively easily.

Does it only show up on the trunks or do you also see it on the soil?

 

[TestoTarzan]

It is not entirely clear from the photos but this is more usually a mineral build up. Being in the glass house often makes it worse because it's warmer so more evaporation from the soil surface. Misting or light watering makes it worse. Heavier watering may flush out the mineral rich water left after evaporation.

Should be easy enough to decide if it's mineral or fungal. Mineral is hard and crusty and can be difficult to rub off whatever it is forming on. Fungal is soft and should rub off relatively easily.

Does it only show up on the trunks or do you also see it on the soil?

More often than not I also find residue on top of the soil. It becomes more visible when the soil dries up, it looks like white dust, in lack of better words, and it hardens over time. Here are a couple of pictures of an empty time in which an affected tree used to live.

 

[Shibui]

Sounds more and more like mineral residue from the water.
I'd be considering heavier watering less often if you can manage it and still keep the trees properly hydrated. Water should run through the soil and out of the bottom of the pot. This helps leach out minerals that are left as water evaporates.
Also check soil and water pH. Calcium is one of the major minerals that causes these scale issues. Calcium also contributes to high pH which can affect plant growth. Other minerals can also reach toxic levels if not leaches out of the soil regularly.