Need help with my new seedlings! Sunken/watery spots

[Orchidreamer]

This is my first time growing seedlings from flask. They are Den harveyanum seedlings that were just deflasked, and they were perfectly healthy seedlings with perfect leaves when I got them. I potted them up in sphag last night, 3-4 plants to a pot, and placed the pots in ziploc bags with the tops slightly open. I sprayed with diluted physan.

Now, 24 hours later, I notice some of the leaves have gone bad! Some of the leaves look watery, as if they're bruised, while others are pitted/sunken, and some of the pitted areas have turned dark. I cut off all the bad portions and dabbed with cinnamon.

The watery bruising reminds me of erwinia or soft rot...what do you think? I made sure to disinfect everything and keep everything clean though. The sunken pitting reminds of mesophyll cell collapse due to cold damage...but the seedlings have not been cold and I have them on a heat mat (65F room temp + 10-15F extra heat).

Should I use stronger fungicides?
Pic 1: before potting up
Pic 2: potted up
Pic 3: I had just been doing leaf surgery 10 min ago.

[WhiteRabbit]

[escualida]

I would have actually used a milder fungicide like Captan - I've read that Physan is too strong and can harm the delicate seedlings.

Another thing might be a lack of air circulation, I know the bags are slightly open but the lack of air movement might have caused damping off of some of your seedlings.

[Orchidreamer]

Thank you for your advice. In the future I will get some Captan for any future deflasking projects.

And I think you're right...my seedlings are damping off. When I checked them this morning, most of the leaves dropped off like flies. The area where each leaf connects to the pbulb is rotten.

Wow, this discouraging.

I wonder, can a seedling survive if it doesn't have leaves? Its pbulb is still alive and unharmed, as far as I can tell, but it has no leaves.

[orchidsarefun]

did you get these in the mail or physically from a breeder? If in the mail they may have been chilled and that is why they have reacted the way they have.
I have had plants sent to me in Winter and even with a heat pack have taken a while to adjust. That is after losing a couple of leaves.....

[escualida]

I'm not sure if they can be saved but I would give it a try, you've got nothing to lose at this point, right?

Maybe find a way to get a little airflow to the plants without dropping the humidity too much. My setup for deflasking has worked pretty well so far. If you want to look at it I described it pretty well in this thread: Help with deflasking I've deflasked 3 times so far and they're doing really well.

I realize that you might not have wanted to spend the money on this kind of setup but it honestly didn't cost that much. I got everything from Amazon.

This is the dome: Amazon.com: Hydrofarm CK64060 Hot House with Heat Mat: Patio, Lawn & Garden

Humidity meter: Amazon.com: Zoo Med Economy Analog Dual Thermometer and Humidity Gauge: Pet Supplies

Captan: Amazon.com: Bonide Captan 8 Ounce: Patio, Lawn & Garden

Fan: Amazon.com: Thermaltake Mobile Fan II External USB Cooling Fan - Us: Electronics

Keep us posted

[King_of_orchid_growing:)]

I'm not sure what the cause of the bruising is. It could be from the Physan, idk.

I can offer this bit of advise, though, Den harveyanum must be grown with a winter dormancy in order for them to do well in the long run. They tend to peter out over time if they're not given a winter rest.

[Orchidreamer]

Thanks everyone for the replies!

Orchidsarefun--the day the plants were delivered it was 50F-70F. However, the plants originally came from a very warm place, so maybe they didn't like the lows in the 50s?

Adriana, thank you for link and the setup idea. I love your setup! I think I can create something like that too, since I already have a Hydrofarm heat mat and a humidity meter. Just need Captan, a fan, and some sort of dome. Currently, I have the plants under T8s on a heat mat, without any plastic bags or humidity cover.

The damaged leaves continued dropping off, so I have a bunch of leafless bulbs. So far I've lost one plant (its bulb started going soft from the top). The others are...alive. Well, alive-ish.

Philip--I've stopped using physan for now, since I heard it can be bad for seedlings. I will definitely be giving them a winter rest when it's time, which is easier for me since that means I have fewer plants to water in the winter. For now, it's almost spring, so I guess I should just let them grow normally.