Mychorrhizea should be concidered experimental at this point IMHO. In theory they are an excellent allie to the rooting system and nutrient uptake of the plant however I have seen some evidence that occasionally a less desirable strain will become dominant and set up shop in the soil matrix. Large voids and cavities filled with fungus populating at the root zone seems to have ill effects on plant growth. I have not begun to study this I only know that in some cases I have had several plants all growing in the same mix of soil, one plant will look less healthy that the rest upon transplanting it becomes clear that an undesirable colony has propigated the root zone. Why when all buckets are drained the same and have the same soil mix and mycrobe innoculatioin one breaks bad on you I do not yet know.
Therefor I say when it works right it is a boon when the colony turns nasty however it can cost you alot of time and worry. Unless you see the problem in the root ball it appears that the plant has some crazy uncorrectable mineral deficiency.
Obviously when you toss a packet of 26 known beneficial microbes into your guano stew some process of natural selection will occur. Who is to say that a mycrobe benifical to oak tree roots would rather dine on cannabis roots than feed them?
I do not know, it is simply a hypothesis.
