I was watching a video on bare root tree planting, and was wondering if you really need to use mycorrhiza if planting a tree/bush.
In general, it is not important, you can't avoid it!
Most farmer knew nothing about it back in the days...
Mycorrhiza will naturally occur in healthy natural environment. If you plant a tree with home grown compost, you do add "mycorrhiza" anyway.
One case I know it is: Truffles
They do this e.g. to grow truffles.
It is important in this case for your crop yield in that case.
I'm sure there are trees that cannot grow at all if they don't have one special mycorrhiza... But then it will be on the roots (even bare) when you plant it.