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A few days ago I realized the previously thought harmless white spots on my 3 month old Lophophora williamsii "Big Bend" seedlings were spreading to almost every seedlings in the pot and are enlarging into patches of white lesions .

Please take a look at these photo and help me come up with a diagnosis. I think I will take them out of the bag regardless the conclusion. What's the prognosis? Are they all doomed? I suspect some sort of combination of environmental (too humid?) / fungal attack are involved. These seedlings are quite precious to me and it would be a shame to lose them.

Looks like this is turning into a painful, harsh lesson for me



For the other 5 seedlings that do not seem to be rotting, I have commenced emergency protocol, pricking out all of them and letting them dry. The plan is to remove any residual seed starting mix around the tap roots and transplant them into a dry mix with high mineral content. Please let me know if I'm missing any steps?

should I slice out the rotting tissue? It looks like a dry rot with intact tap roots. A little probing tells me that the rotting zone is NOT soft or mushy.

What could I have done wrong that lead to this cluster***k? I think the simplest answer is too much moisture and humidity, possibly poor sterilization of the germination mix. This puts a dent in my trust for the baggie method, though it is the only viable option for me since I don't have access to fungicides like chinosol (C&D) or superol (forgot where I saw this). Basically, I relied solely on environmental sterility...anyways, I'm rambling.

I never have any success with the baggy method. It could be rot or too much light even. I tend to use a pure mineral mix so less chances of fungi attacks. I keep them in a home made light box which is one of those big plastic storage boxes with a lid and lights fitted in to the lid. It does get humid but the open pots tend to move the water around with evaporation in the day which condensates down the side of the box at night so I do have to manage the dampness of the pot manually. It is a little more effort but it works.

I have used the baggie method for L. williamsii successfully by removing the seedlings from humidity after 1-2 months. The extended time you've left them in the bag paired with the seemingly very organic substrate probably caused this issue. Before sowing I wet the medium and microwave for 1 minute (sowing in individual, 2-inch pots). Also I might suggest sieving your organic medium, it appears quite mulchy. Ideally you want something fine without large pieces to hold moisture.

Ade is a strong supporter of a purely mineral mix for Lophophora, however I have had quite nice luck so far with 2:2:1 limestone chips:pumice:soil.

HP22B wrote: Ade is a strong supporter of a purely mineral mix for Lophophora, however I have had quite nice luck so far with 2:2:1 limestone chips:pumice:soil.

I am having my best result with home grown seeds got a good number of williamsii, diffusa, jourdiniana mixed seeds coming up in one pot and koehreshii and fricii albiflora in another two pots all on a high limestone pure mineral mix. My only issue is since the household heating is being used now the cold is setting in the temperature is a bit higher in my light box so am now getting a little bit of algi growing on the surface. I usually fix this with another layer of limestone chippings (sandy bits not greater than 1mm but not dust) and cover it over. I just need to wait until I'm sure no more will germinate.

Thank you both, it certainly warrants drastic soil and environmental adjustment in my next batch of seeds. right now, I am doing everything I could to save this batch of seedling.

I transplanted them in dry, mineral rich medium in small pots under indirect lights. How long should I leave them like this before introducing them to water? Can I still save them?

Obviously we can't see your potting mix, but they look so much better. My guess is that they will be fine.

Steve

If that top soil is the same all through the pot you should be good. If you can just give them rain water that is the best but they look much better there. The roots will heal quickly with young seedlings so just keep them warm and in a few days you can give them a drop of water to stimulate root growth just be carefull and only add more water when it's dry.

A tip is to weigh the pots now if you can, then you have a dry weight to compare with to know how long drying time the pots have. Then it is much easier to establish a good watering regime to your seedlings. I also grow mine in mineral media, like adetheproducer, and I don`t do the baggy method, and have rarely lost seedlings to fungus or rot. I just don`t think the benefits of having them closed up is worth the increased risk. Some slow growing species gets tricky with breathing freely thou... like Aztekium and such...

Appreciated all the input, quite insightful. I have a coffee scale handy, so I'll use that to weigh the pot for sure.

My apologies, I should have posted an image of the medium earlier, here it is. It's not 100% inorganic but has a significant proportion of chunky volcanic minerals.

That will probably be ok for the seedling stage but when they get a bit bigger you could lean it out with more minerals and loose the organics. You might want to add some limestone to the mix as well it keeps them in a nice compact and natural looking shape. The organics does cause them to bloat up a bit.

Do sciarid fly larvae cause lesions like this?

I don't know your growing conditions but you should be very careful with waterings during the winter. Plants must be in warm place with enough sun or bright light. I have lost several ones of similar size because of overwatering before cool and cloudy weather. It's good that you changed that dump soil from first photos.

Thanks, the good news is that I am growing them under warm temperature and artificial light. The bad news is a week after the initial transplant, they adopted a purple/brown complexion and have become wrinkly and squishy (not mushy).

Reduce the light and let them rest if it's rot they will collapse. If they are just light stressed they should go back green or cork over and pop a new head out of the up most areole in my experience at least.