Saving seedlings from mould?

[MatDz]

As my post history might tell, I have recently sown a batch of seed list seeds (from here and the MSG) and while most of the pots look pretty promising, I am afraid I contaminated two with mould spores.

Aylostera heliosa condorensis already germinated two seedlings (marked with arrows), but there is also a large patch of mould in the pot (red circle) - is this fixable, preferably without hard to obtain and not necessary fully legal substances?



Even worse situation happened to Ariocarpus retusus, where I cannot see a single seedling (it's a week after sowing, so it's not that surprising I guess), but instead I managed to grow a nice layer of mould. I'm pretty sure this whole pot is a goner, but maybe I can open the bag and dry out the mould and start over?

[habanerocat]

This thread may be of some interest.

https://forum.bcss.org.uk/viewtopic.php?f=1&t=162843

[Chris L]

If I saw that in my pots I wouldn't be too worried (maybe I should be?). I do get some mould, but more usually moss and algae on the surface of some of the compost, usually those where nothing (or very little) has germinated.

I don't do anything fancy to my pots & compost - just stand in a tray of boiled water until the compost is soaked through.

If your pots are in their own bags I'd be tempted to wait awhile to see if anything germintates. If nothing germinates then probably best to start over with new seed.

It sounds daft but sometimes it is good to have pots that don't work out as otherwise there would soon be nowhere to put the resultant plants.

[Licespray]

I boil the whole pot of soil with a lot of water in it on the stove. Then I put that in puts in the baggy. Seal it and then the next day I put the seeds in. Sometimes get algae, yet to get mould.

[Flayzerflay]

If it was me i would put a tiny lid over each seedling to keep them humid while you air the top.

The other option is to cover the seedlings one by one and spray the top soil with hydrogen peroxide 1-2% , this will fizz and kill the mould, then take lids off,pen lids, led covers, toothpaste lids, all work.

[Kees]

Next time microwave the soil and put the seeds in some iodine tincture for a short while.

[Phil_SK]

These sorts of moulds are feasting on the organic matter in your soil and probably won't bother your seedlings. If it bothers you, you can periodically open the bag and let the soil surface almost dry out. Although cactus seedlings thrive in the wet and at 100% humidity, they are remarkably tolerant of drying out once they're a few weeks old. The mould will come back when you rewet and reseal but your seedlings will steal a march on the mould each time you do it. However, you riisk introducing other things - moss, ferns even.

[MatDz]

Thank you everyone! Some selected follow-up questions and thoughts below:

This thread may be of some interest.

https://forum.bcss.org.uk/viewtopic.php?f=1&t=162843

Ugh, that looks exactly like what I would rather avoid at this stage, but thank you for the link - well worth reading and bookmarking!

If I saw that in my pots I wouldn't be too worried (maybe I should be?).
[...]
It sounds daft but sometimes it is good to have pots that don't work out as otherwise there would soon be nowhere to put the resultant plants.

That's definitely one way of looking at this I think I will just wait things out as you suggested, I'll post an update below - things are not looking that bad!

If it was me i would put a tiny lid over each seedling to keep them humid while you air the top.

The other option is to cover the seedlings one by one and spray the top soil with hydrogen peroxide 1-2% , this will fizz and kill the mould, then take lids off,pen lids, led covers, toothpaste lids, all work.

I do have plenty of suitable pens, but won't that hurt the seedlings through the soil?

Next time microwave the soil and put the seeds in some iodine tincture for a short while.

No microwave I am afraid, but sterilizing the seeds might be worth the effort - maybe just H2O2 would be enough?

[...] If it bothers you, you can periodically open the bag and let the soil surface almost dry out. Although cactus seedlings thrive in the wet and at 100% humidity, they are remarkably tolerant of drying out once they're a few weeks old. [...]

The problem is the few that germinated already are maybe a few days old, and I hope many more are still coming!

Update after 1.5 days:

I can see at least 7 Aylostera seedlings, including one right in the middle of the mould patch (which makes me think it was the seed!), I think I will try the pen lid ventilation or H2O2 treatment in a few days, but first want to give them more time to germinate.



With Ariocarpus, I see one seedling in a spot free from the mould, so the plan is the same as above - wait a few days and see how the situation evolves.

[MatDz]

I have posted this on one of my other posts, but it fits the subject very well, so let's try here as well:

Below is an update on my Lophophora williamsii seedlings having some mould issues:



What would be the best treatment to that? Two I am thinking about giving a try, mentioned earlier here, are:

• Spraying with diluted hydrogen peroxide (1-2%); and
• Opening the bag to let the substrate dry out.

I am not sure whether the second would work with the opinions that when once opened, the cacti have to stay out. Maybe it's time?

On the hydrogen peroxide, I would love a second opinion, as it sounds a tad harsh for the seedlings and I don't think I can cover them at this stage - they are too big!

[el48tel]

You could try an anti fungal spray