How old, Jed? Are the seedlings still young enough to damp off?

Since you're posting this I'm assuming you've ruled out the obvious---too much water, too little water, too much fertilizer, too much bottom heat or too much cold.

If the damage is directional (left to right of the tray, for example) it might be a pathogen in the soil triggered by temperature drop, fungal most likely. Dig up the healthy ones and pot individually in fresh substrate.

I strongly recommend taking one of the damaged ones and slicing it across to expose the caudex tissue so we can see what's going on. Fungal or bacterial damage usually looks black or dark and starts in the center of the trunk if it is something in the soil being absorbed by the roots. They have a ripe odor too. Sometimes if it is gas-producing bacteria, the sap will ooze if you break the tissue.

I can't make any more speculation without more information.

I hope we can all figure it out in time.

Pagan

Add...oh. two months, duh. Too old for damping off. It could be rot then, which does start from inside and nearly always result from too much water.

Caudex rot that starts from outside is actually quite rare, resulting from breaks on the skin which air-borne pathogens then take advantage of to get into the plant.

P

Yes, Collar rot in Adenium seedlings does start within. The stems will become soft/squishy with no visible color change to stem. They begin to shrink at this point (usually above soil line). It is known with many of the Australian growers and believed to be a soil Bourne issue.

I have had heard them speak of trying a light wash w Peroxide and water? Also spoken of possibility of lack of air to root system?

Sorry Jedoba, these are not answers to your strife with your seedlings, but just information I had asked about and received.

I think as Pagan mentions, change of soil may be the best alternative to save them.

Rick

Thank you both very much. You confirmed what I feared because of the way it is moving through the tray. These were strong seedlings and each weakens within hours, one after the other, like dominoes. Other trays centimeters away are unaffected.

I will probably try a light mix of peroxide and water, and then repot separately.

Thank you both again very much.

This tray was dryer than I usually allow before I started seeing the rot. I let it get pretty dry after that hoping to stop the rot. I removed the rest of the two affected rows, placed in another pot, and watered. Those are gone already. Then I watered the tray as normal. That tray still appears ok, so I assume the problem may have transferred via contacting roots. (I took one seedling, and replanted it in the same area as the mass death, and it is still firm)

Funny thing is that the roots were healthy and white on all of them. They just got squishy caudexes, and wilted over.

I was particularly worried because this tray contains my 'twin' seedlings.

Jerry,

Has it been raining a lot where you live? If so, consider that overnight rains this time of year can be rather cold & clammy.

Young seedlings can also react unfavorably to a change in temp, sun intensity, lower humidity. I've experienced a "soft" caudex on 2 similar-age seedlings. Here's what worked for me.

- Remove from soil & rinse off

- Allow to dry 24 hours

- Lightly sprinkle everything below the leaves with an anti-fungal =》 Powdered curcumin/turmeric, nutmeg, cinnamon are effective (listed in order of potency).

- As well indicated, individually repot in new soil with added perlite to improve root aeration.

- Water thoroughly and return to original growing conditions.

- Only water when the top 1" of soil is dry. Keep out of soaking rains.

- Watch the caudex ... It should harden up in about a week ... don't give up on them.

I hope they bounce back for you.

Maria Elena

Wow this post came just in time! I've lost a few seedlings to that and I had no idea what was it... Now I have one tiny mini that suffers from soft shriveled coudex and I was about to toss it. Thank you Mari Elena, I'll follow your advice and hopefully save this little one. Mine are indoor on a heating pad and under LED light, really didn't expect that to happened this time... probably something in a soil. How's your seedlings doing Jerry?

I have one that is a bit soft. I think it might make it, and the others all seem ok.

I hope yours recover.

You might also want to consider mycorrhizae. Since Trichoderma (a commonly included fungus) eats other fungi, it can help with reducing fungal diseases like damping off and rot.

Probably not much help after the rot takes hold, but it can be a good preventative.

I kept my adenium's soil wet enough that yellow mushrooms grew next to it, and it's still totally fine. So, there is something to be said for getting good microbes to crowd out bad ones.

If you wanted to see how a dying seedling would have flowered, you could always try grafting a tip so you at least save that much.

Thanks! I don't know much about beneficial microbes, so that is great.