Thomas wrote: Mycorrhiza spoors can certainly be present in the vacinity of where an inoculated plant was planted previously and they will re-infect a new host plant, but to a lesser degree than adding another charge of inoculant when new plants are planted each year. Er, don't wish to be a nit-picker, but I think you mean "spores" instead of "spoors". The meaning of the sentence is quite different if you're referring to "spoor" <bg>. I'm a results oriented person... not a scientist.... but when I put an inoculant on a plant I just observe that plant's performance. There is performance above ground that is easy to note and there is performance below ground that is more difficult to note. I've set up experiments with plants so that I can observe what is going on with roots as time goes on. What do the roots look like at the end of the first, second, third, fourth etc., weeks? A lot of replication has to be set up to make those observations. When I see the root system of a plant take of with an explosion of very fine root hair structures that normally are not in uninoculated plants.... a process that fits mycorrhiza and not any other micro-organizim, then there is an effect. I don't care which species is causing it... I'm interested in the fact that the results are present in my garden plants. There's nothing wrong with anecdotal reporting. But it's just that: self-reporting of your personal experiences in your individual plot of land. The fact that you have a commercial interest in the outcome further clouds your abilities to observe and report without bias, however unconscious that bias may be. The old saw about how lab results are 'corrupted' when the investigator stirs the pot with his/her own finger applies. All that being said, I do believe in mycorrhiza innoculation for specific crops. I just don't support posts that promote the self-interests of the author who is also acting as a sales agent for the product. You don't have to put a URL in a signature line to be guilty of advertising on a non-advertising mailing list imho. Catharine, Atlanta/zone 7b