An excerpt from my interview with Dr. Elaine Ingham. Thanks to Todd Hoff for the transcription.
Bacteria and fungi are really good at holding nutrients in their bodies. If you don’t have nutrients in the soil then you need bacteria and fungi. They also put up castle walls to protect plant root systems from insect pests and from fungal and bacterial diseases. The plant itself puts out certain kinds of sugars and proteins and carbohydrates to build that castle wall. By exuding different nutrients it attracts different bacteria and fungi to protect against particular diseases or hold certain nutrients. The plant has a lot of communication and control of what goes around its surfaces. Plants know how to protect themselves. You don’t need pesticides.