A subscriber in Wisconsin writes: "Enjoy your newsletter and appreciate your product. You stated 'When the right types of mycorrhizal fungi are matched up with the right host plants...' Perhaps in your next edition you can explain what the matches are and how one achieves them."
Well, I'll try. The most basic match is with Endo or Ecto-type fungi, and in very general terms most of the plants on Earth, more than 90%, match with Endo types. Ecto-type fungi match with pines, oaks, birches, and a few other plants. There are also specialized types of mycorrhizal fungi - orchids have their own type, plants in the Ericaceae family (blueberries, azaleas, rhododendrons, heath, heather) have their own type fungi (not available in inoculant form, as far as I know), and it seems that mustard and cabbage-family plants do not form mycorrhizal relationships (although the mycorrhizal fungi will gladly scavenge dying cabbage roots to take those nutrients to host plants).
That's about where the agreements end, and I wouldn't be surprised if I hear from someone telling me about errors or omissions in the paragraph above. For example, I'm aware of one soil scientist who states that she has found Ecto-type fungi on grape roots, and I wouldn't doubt her. Another well-known scientist told me that he doesn't even bother trying to get into all the complex details of this topic - that he can see people's eyes get all glazed over when he does.
The practical view - which is the orientation of my newsletters - is that farmers and gardeners need Endo types, and they should examine inoculant labels to make sure Endo spore counts are guaranteed. (Be careful about labels that give a combined count of Endo and Ecto types - a billion tiny and inexpensive Ecto spores won't do a bit of good for a tomato plant.)
There are currently more than 150 named types of Endomycorrhizal fungi. The great majority have not been seriously evaluated for their effects on plants, and certainly not on a wide variety of plants grown in various types of soil. I have personally observed great variation in benefits to identical pot-grown plants when different types of fungi were introduced to roots - all the way from not differing from the control plants to showing dramatically better growth and yields.
This sort of grow-test would allow us to choose a predictably-good fungus for more of those plants in that same growing medium, but how about when those plants are in other soils? It might not be the same. A tomato in New Jersey soil and that same variety in California's Central Valley will both benefit from mycorrhizae, but is the same fungi the best choice for both? Maybe not.
BioOrganics puts eight Endo types in all of its inoculant products. This inclusion of several types of spores makes the most sense for producers of packaged commercial inoculants. A "shotgun" approach may seem unscientific, but it works. Maybe some day we can customize inoculants for regions or even for specific crops within regions, but not yet.
Interesting subject. I expect we'll be able to put a finer point on it in the future.
Cheers, and good growing,
President, BioOrganics, Inc.