OK, don't know how to respond to that...
First, I was thinking out loud, rather than thinking it out then posting, so it's very possible I got something wrong. I was also plugging some ideas together, so it's possible you misunderstood what I said... My statement might have been better punctuated....
We are talking about endomycorrhizal fungi that do not exist without plants. Period. They get food from plants, and when the plant dies, they die.
and I said:
... that form beneficial symbiotic relationships with living plants (as that seems to be the working definition of mycorrhizae)
Don't these two statements sound similar? Note that when I underlined the "and" I meant if they "also" etc. above, then all the better. I didn't mean to imply that "saprotrophic fungi that only feed on dead organic matter" and mycorrhizae were one and the same. I don't know if they are, you said they aren't. I'll accept that. Yeah, now that I look at it, it's confusing.
As for the white furry thing -- I don't know why it has
to be mold. Seriously, if you look at all my oyster mushroom and shiitake hyphae/mycelium growing on agar media, sawdust, and woodchip substrates, they're all furry and white. Most of them are in my bedroom right now. So, seeing them day in and day out, you tell me white and furry growing in mycorrhiza inoculated soil and I automatically think "mushrooms!" -- rather than mold.
I don't know where decado got his stuff, but Fungi Perfecti sells mycorrhizal products. I kind of assumed that at least some of them are a by-product of mushroom cultivation (like the way they collect BAGS of spores from the filtration system and now sell spored oils.), though I have no basis for that assumption. I mentioned elsewhere the P. Stamet's Brussels Sprout bed inoculated with H. ulmarius research that boosted yield and size, as well as how P. eryngii has symbiotic relationship to carrot family plants.
Also, my TP tube-as-bottomless tall/narrow pots have started growing mold-like patches after I watered them with spent oyster mushroom substrate extract. It might be mold, it might not. I've been watering with AACT to increase competition and the patches haven't grown any bigger though they haven't disappeared entirely. These have onion seedlings in them, and they looked a little stressed initially, but now they are looking happier. As long as the cardboard tubes are getting broken down, I don't really care what's doing it.
If I'm still wrong, then I guess I'll just have to finish reading that book and try to catch up.