I've tried to scale down a single fruiting medium to 100-200g, and it keeps failing time after time: at best, I get small needle-sized fruiting bodies (hypsizygus tessulatus, post picture) or primordia and then small malformed underdeveloped fruiting bodies (pleurotus eryngii, inline picture). Then development just stops. Medium is enriched (sugar) alder chips, contamination starts developing long after growth is stalled. Is it really scale problem? What's the reasonably smallest batch size?
The long fruiting bodies that just abort are because it's starving for oxygen. Remove them from the glass jars and put them in a box that's kept humid (like a plastic container). Look up "shotgun fruiting chamber". Or you can crumble your entire cake into a bin with some coco coir (contamination resistant) and the mycelium will spread and quickly start forming hyphal nodes and then fruit properly.
You got this!
But... but... they are in that humid plastic box! And the whole point of this experiment was to see whether I can run 100g media batches really; I had huge fruitings in these boxes just filled with autoclaved wooden stuff. The needle-like fruits do look like they are starved for oxygen; the horizontal ones started growing that way because they were loosely covered with foil (thus no light but full ventilation) - after I removed it I've got normal straight ones, but they still did not develop any gills or anything, just stopped. I suspect it's something else. Almost like it just ran out of energy too soon, didn't even have enough to retreat the mycelium - it's one solid and seemingly inert block now (it's been like that for some weeks; I have older attempts stuck like that for good, chunks of glistening white mycelium that doesn't even rot)
Your jars probably over-colonized because there wasn't enough surface area getting proper ventilation/evaporation to trigger primordia formation so it just kept colonizing. It looks like pins didn't start until the mycelium grew over the top of the jar and by then all the food was already used up.
Topfruiting jars isn't a great method even for terrestrial mushrooms, I imagine it's worse for oysters. Consider using small oven bags instead, that way you can cut the sides to trigger fruiting earlier and across a wider surface.
Thanks; I'm thinking about overcolonization indeed - Stamets mentions that growing in jars works, but mine here are just too small. Colony was supposed to hit the bottom and feel constrained, not grow up. Another thing is heat balance, which is not so obvious; the best results I've got were when I left the house for 2 days in the middle of the winter and temperature dropped by 2C. I mean, I expected small jars to radiate heat better, but then fruiting is surface process, maybe it's the opposite too.
I'm also trying to come up with something that does not use disposable plastics. I know bags are quite versatile, I just hate them, not so much because of ecological issues, but like I can't really make them myself, that's disturbing.
Plastic buckets drilled holes are good reusable option. If you want to avoid plastics all together you could use some of this spawn to plug a small alder log.
I had troubles with logs - I have lots of trees, but apparently most are already badly inoculated. Or I need to choose really really healthy looking ones. Or dry them first maybe.
I haven't tried myself but my understanding from reading Stamets is that you're supposed to cut the log and move it to a wood shed or something right away without letting it sit on the ground for an extended period. Alder is supposed to decay much quicker than other hardwoods as well so it's not used as often.
To throw out some easy options, in a humid chamber, a plain cardboard box roughly the same volume as those jars would do great, especially with a few 1/4” holes added.
A closed 12-ct paper egg carton with a few holes where you want fruiting would also do nicely, but that’s probably right on the line of minimum growth medium necessary for decent fruit.
And if you get bored of the scaling-down experiment, you’d be well served with some 3-gal food-grade buckets with a few 1” holes. Still plastic — but readily available, indefinitely reusable, and should fit your chamber nicely!
Yeah, I'm thinking in direction of edible (for mushroom) containers; maybe some cardboard origami, or simple wood plank box; I'm even thinking to try casting linoleum pots on woven jute. It must be doable, why nobody does that now?
Definitely doable! I learned how to grow through a class hosted by my local myco society, and they made a point to show us oysters growing in + on all sorts of wacky things. Shoeboxes, laundry baskets, water-damaged homes, etc.
Just hard to beat the cost of plastic grow bags at scale :).