Seedling problem, too much Ca?

[athos]

Hello everyone.

I have a couple of seedlings that are 12 days old since breaking soil. One of them has a weird problem on a couple of older leaves, I don't know how to call it, it's like chunks of it are peeling off and the leaf becomes brittle. Here is a couple of pictures of it.

Now, I'm using soil, Biobizz Allmix and watering every 5 days (at day 0, day 5 and day 10) with water with Cal-Max (total EC of 0,4), I'm using this because last run I had a severe case of calcium deficiency because my tap water is 0,04 EC (20 ppm), maybe it was too much or too often? it's the only thing that I can think of. The other seedling has shown no problem. Here is a picture of the affected plant of 3 days ago (at day 10)

 

[Rev. Green Genes]

are there any signs of insects? check the bottom of the leaves for spots. It looks like gnats to me.

If not, it is most likely a pH issue.

 

[namvet25]

Hold off the cal/mag for awhile.

 

[athos]

Thank you, I came to the same conclusion. I did a light flushing of the soil and took out the affected leaves, today it looks much better.

 

[Waira]

Athos-- I've seen this weirdness before, and couldn't pin it down for cause in any case; for the tissues to die so fast they don't change color and go crispy right away doesn't fit any nutritional issue I can think of, so that leaves physical/env. issues...... too early for defc. issues in that soil anyway,... this physical damage, it's called mesophyll cell collapse (inner cells between top and bottom epiderm/cutilce layers).... only known cause for it I've seen is very cool drafts across the leaves,... I see it in other plants too.... But for canna, aside from the one that my friend left in a window with cold air hitting it overnight, the others had OK temps, so I'm stumped,... is it advancing, and occurring overnight?

 

[athos]

Thanks for your reply. It's hardly a temperature issue, singce it's summer here, at night (lights on) the temperature reaches 29°C (84 F) in the grow box and during the lights off period (2pm to 8 pm) the temperature "drops" to a minimum of 22°C (71 F).
I did a minor flushing, and the seedling is looking great. I also plucked the affected leaves since they were dying anyway, but there's new healthy growth and I was planning to defoliate the fan leaves anyway to promote the side shots to develop.

Here's the affected seedling 3 days later at day 15

 

[Waira]

... well, that's that! Don't defoliate the leaves so young, look into so called pony-tailing to promote laterals growth,... those fans are energy centers and nute storage, chopping them off so young will not be helpful,.. later, if larger and plenty of good leaves, the impact is greatly lessened,....

 

[athos]

I'll leave the other seedling be and use it's as control to compare the results to see if defoliating does something useful or not.