Arghh!! 600 seedlings wiped out - what is going on?
 

Folks, In my 10th year of successful germination, my seedlings this year are destroyed by a mysterious death of the growing tip. The roots are fine - the stalks are straight, but the growing tips have died. See pic.

The only thing I did differently this year is wash the soil with hydrogen peroxide and mist the top with 50% HP solution to stop the dampening out problems I had last year.

Could the hydrogen peroxide have done this?

My first thought was heat from the lamps, but I use t12 flourescent bulbs and the heat was low, and the bulbs were not too close to the seedlings.

Yes. Most definately.
KarenO

Yes Yes, Amen!!
I would never use hydrogen peroxide!!!!!

Ya, misting the seedlings with H2O2 must have done it.
For the same reason you treated the soil with H2O2 to kill pathogens you feared might be in the soil, H2O2 causes plant cell death in the tender seedlings.

Maximum concentration of hydrogen peroxide that can be used in gardening is, as far as I know, 3%. To be safe I use concentrations up to 1%. I soaked my seeds in HP before they went into the mix for half an hour and they are shooting fine. The problem is concentration, not HP in itself.
Milan HP

50% hydrogen peroxide is awfully strong!

I think you may have been fine if you had just washed the soil like you did and did not spray. From what I read the main action and benefit of hydrogen peroxide is to the roots as it adds more oxygen. Spraying as Ray stated is usually used as a pesticide.


It is also possible as others said the mix was to strong.



While I was reading I saw that tomato plants actually produce hydrogen peroxide as a defense mechanism. I had so many tabs open I lost that page





Here is an experiment a high school student did


[URL]https://csef.usc.edu/History/2013/Projects/J1717.pdf[/URL]

Ugh Scott...so sorry for your loss. It's not too late to start again, is it?

No, I re sowed last night - luckily, I had enough seeds. NO HP this time!!

[B][SIZE=4][FONT=Garamond]Hopefully, round two will be round one's redemption![/FONT][/SIZE][/B]
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:)

[QUOTE=ScottinAtlanta;767320]No, I re sowed last night - luckily, I had enough seeds. NO HP this time!![/QUOTE]

I am glad you had a backup. Do you have any Heirloom Buckwheat Seeds? I use it as a crop cover but had a customer who wanted seeds, and I did not save seeds they just come back each year. I found out today that it was also grown here in front of Fort Monroe in another location around 1964.

I am also glad you had extra seeds. Those pictures were so sad.

Hey, look, it worked. No damping off...


You are like me, you experiment with the whole tray.

Bummer, and I'm very sorry for your loss. It looks like it will only set you back about a week.

You called what you are starting seedlings in as "soil". My question is, are you starting seedlings in a so-called "soilless " mix (like a peat-based one) or something else?

I use h2o2 for my seedlings always, to prevent damp off. A very weak solution. One and one half teaspoons of 3% h2o2 for one cup of water. 50% is way too much.