it isn't cheap, either. scroll to the bottom of
this page.
I think in some circumstances it could work pretty well. to grow
mushrooms on logs, all cut surfaces are generally either sealed somehow, or kept in contact with moisture. leads me to believe that if any steps are taken to dry the wood out relatively soon, rot won't be an issue.
an example: I'm dropping a Doug-fir (paul's favorite) for
firewood. it's not a suckering species, so it won't coppice. I use the spore oil in my saw so the stump is inoculated. I can either swap saws, or just swap oil for bucking the tree up into stove length, so only the very bottom round gets any spores on it. or I don't bother switching and there are spores on each round (waste of expensive spores). then I split it all and stack it to dry. the stump grows some Phoenix oysters for a few years, the firewood dries and grows nothing and I burn it. no problem.
I don't know how effective this stuff is. folks tend to go to fairly great lengths to successfully inoculate logs with mushroom spawn, so I would imagine that the success rate with just spores isn't terribly high. in a thinning situation where a lot of
trees are cut to make room for the remaining trees, I could see it working fairly well. the trees are thinned, nutrients are cycled, and the mushroom harvest of the forest is increased (though who knows to what degree?).