I just had a conversation with Scott Woodbury from the Shaw Nature Reserve about their use of Mycorrhizae in the production of their plants.
They initially use a potting mix which is 50% mix from St. Louis Composting plus 50% BX-ProMix. BX already has some Mycorrhizae in their mix.
When they transplant the seedlings to their own pots, they add Mycorrhizae. The brand they use is http://mycobloom.com/
He has had good results with this brand. Scott wrote am interesting article about Mycorrhizae in the Kansas City Gardener.
While the initial price of this product – $20 for two pounds, seems a bit high, when you consider that many plants cost $10 or more, then if you could save just a few plants using Mycorrhizae, then the price would be justified.
Scott did mention that they had not done field tests, but that they great results in the greenhouse.