As it happens, I have had some personal experience with mycorhizal fungi, and while I don't know the gentleman who spoke to your group, my contact in Camarillo, CA was very honorable and knowledgeable. After his reading my newspaper column and finding that I was amenable to conducting a small experiment, he provided me with a sample of his product. Since my garden is very small (I live in a mobile home park next to the beach), I confined my esperiment to 6 Celebrity plants and 4 Roma plants, putting some of the fungal culture into the holes of half of the Celebrity and of the Roma plants. Other than that, I used the same cultural practices on all of the plants. The differences between the two test groups became noticeable in about 2 to 3 weeks, and the final result was so convincing that I can testify that the inoculation of the soil with microrhizal fungi made an amazing difference. In addition to producing noticeably healthier plants, the treated Roma plants yielded twice as many tomatoes, and the Celebrity plants that were treated yielded 5 times as many tomatoes. In addition, the treated tomatoes bore fruit at least 3 weeks longer than the untreated ones, and the total weight of the crops were in about the same ratio as the number of tomatoes. This experiment was conducted about 3 years ago, and a brief report was published in the Journal of the Master Gardeners of Santa Barbara and Ventura Counties. We had an agreement to run a more intensive experiment with an acre of tomatoes of various varieties, but I had other commitments (I am an Orthodox Priest, and had to take over a church located at some distance from the test garden), and unfortunately the experiemnet was cancelled. I give you this information for what it is worth to you. In summary, I can truthfully say that I am sold on the usefulness of microrhizal fungi, as are the farm advisors in this area.