Is this damping off

[tnkrer]

I am starting my second batch of cucumber seeds and once again the seedlings have failed after showing great sprouting. The seeds were on DE and the tray was covered and on seedling heat mat until the sprouts popped. Then the heating mat was removed and the tray was on the south facing window sill where it gets sun for 4-5 hours.

Is this what damping off looks like? what can I do to prevent this? One interesting observation (could be of course coincidence) is that both times 3 out of 4 saved seedlings (two varieties, an unknown pickling cuke variety and burpfree) died this way, whereas 4 out of 4 seeds (diva and poona kheera, bought from pinetree) did just fine. You can see the chard also doing just fine. So is it how we save the seeds?

[kath]

Yes, it's damping off. Letting the top of the soil dry between waterings helps; using "sterile" mix and clean, bleached trays; spray soil surface with diluted hydrogen peroxide.

[gssgarden]

yep. When you see them 'break down' right around soil level and bend over.

Greg

[RayR]

Why does the DE look brown in color in those photo's?

[Riceloft]

I haven't had a single damping off issue since I started using Worth's peroxide solution method. I want to say mix water:peroxide in 9:1 or so ratio.

[luigiwu]

Originally Posted by Riceloft

I haven't had a single damping off issue since I started using Worth's peroxide solution method. I want to say mix water:peroxide in 9:1 or so ratio.

what does this method entail?

[Father'sDaughter]

Originally Posted by RayR

Why does the DE look brown in color in those photo's?

I know -- is it just the lighting, or is it brown? Isn't pure DE typically light gray when dry and a darker gray when wet?

[RayR]

Originally Posted by Father'sDaughter

I know -- is it just the lighting, or is it brown? Isn't pure DE typically light gray when dry and a darker gray when wet?

Yep, white to light gray when dry for pure DE. Darker gray when hydrated.

[KarenO]

you'll have better luck direct sowing them outdoors. there is no need to sow them indoors in June and they don't like to be transplanted either.
Karen

[tnkrer]

Karen,
I am going to try direct sowing again this time. My failure rate is close to 100% with direct sowing so far . Last year in my containers, I tried direct sowing 5 seeds of cucumber and none showed up.
This year, eirect sowed a bunch of annual flower seeds (close to 60 seeds) two weeks ago and I have 7 plants to show for those

RayR .. That's how wet DE (ultrasorb) looks. It could be lighting. I will take a picture in daylight. (dry DE is light gray)
ETA: Looking at the photos again, and yeah, its looking brown, not how it looks. Photo was taken at night in yellow light.

Riceloft, I will search for hydrogen peroxide solution method

[Riceloft]

Here's a post from Worth a few months ago:

Originally Posted by Worth1

I know I am starting to sound like a broken record but any chance I get I will tell folks.

If you Keep your seed starting mix moist with a solution of hydrogen peroxide every now and then they wont damp off.

The mixture is 1 part hydrogen peroxide to 9 or 10 parts water.
You can just eye ball it.
It works and it is cheap.
My plants are cold at night and very damp.
If you do this and keep the soil moist you will not have as many so called helmet heads either.
You should never ever let the seed starting mix dry out.
If that seed is in the middle of germinating and it dries out it will die.

Worth

[tnkrer]

Need to ask Worth if the hydrogen peroxide he uses is 10%, 3%, 35% ..
Whatever you can buy at a pharmacy OK?

RayR, in daylight, the wet DE looks gray, not brown

[Riceloft]

Originally Posted by tnkrer

Need to ask Worth if the hydrogen peroxide he uses is 10%, 3%, 35% ..
Whatever you can buy at a pharmacy OK?

RayR, in daylight, the wet DE looks gray, not brown

I just used the stuff right from the pharmacy and had no issues. I think its the 3% stuff. Not 1 case of damping off.

[KarenO]

...I don't see how those can be transplanted without disturbing the roots which will kill a cucumber seedling virtually always. If I start cucurbits indoors I always use peat pots so they can be planted pot and all with no root disturbance. Forgive my old school ways but DE and Peroxide etc. seems so unnatural and I think since the high tech methods are not working for you I would recommend a step back to the natural formula: seed+ soil+ water + sunshine= cucumbers
In June, even in Northern Canada, cucumber seeds will grow fine if planted right into warm soil in the open garden. If you wish to start them indoors, sterile potting medium, moist not wet in peat pots and transplanted pot and all as soon as they have one set of leaves.
I don't understand why all this artificial business is necessary?
Maybe I am missing something
Just an opinion from an old school master gardener from Canada
Karen

[RayR]

Originally Posted by KarenO

...I don't see how those can be transplanted without disturbing the roots which will kill a cucumber seedling virtually always. If I start cucurbits indoors I always use peat pots so they can be planted pot and all with no root disturbance. ut DE a Forgive my old school ways bnd Peroxide etc. seems so unnatural and I think since the high tech methods are not working for you I would recommend a step back to the natural formula: seed+ soil+ water + sunshine= cucumbers
In June, even in Northern Canada, cucumber seeds will grow fine if planted right into warm soil in the open garden. If you wish to start them indoors, sterile potting medium, moist not wet in peat pots and transplanted pot and all as soon as they have one set of leaves.
I don't understand why all this artificial business is necessary?
Maybe I am missing something
Just an opinion from an old school master gardener from Canada
Karen

I don't like the idea of disturbing the roots of cucurbits either, that I agree with.
About the only use I have for peat pots and the like is for starting cucumbers and squash indoors.
Only a few people have reported damping off in DE as a seed starting medium which makes me wonder about the source of the inoculum. Is the pathogen seed born or are the spores just prevalent in the environment. Air borne or water borne? It has to come from somewhere whether it's fungal or an oomycete.
DE is no more artificial than perlite or vermiculite, maybe even more so since it doesn't have to be altered with high heat to make it usable.
Most people who have been plagued by damping off pathogens over the years have reported much better results from DE which hasn't surprised me since using silicate materials is an old school method of retarding damping off. Other silicates like coarse sand and bird grit are used on top of seed starting mediums by some folks including one long time commercial greenhouse herb grower I heard in an interview on the Internet. Many hydroponic growers also use Potassium Silicate in part to ward off damping off.

If using a safe mild diluted oxidant like Hydrogen Peroxide helps to kill pathogen spores on seed or in the medium, I don't see any harm in that.