Adding Mycorrhizal fungi to your soil when planting will enhance growth and and development of the plant's roots which creates greater resistance to disease and drought. Mycorrhizal fungi has occurred naturally in the soil for 400 million years. Mycorrhizal fungi form a close, symbiotic relationship with plant roots. However, in most soils that have been disturbed by residential construction or intensive applications of fertilizers containing pesticides and other chemical products, the mycorrhizae content has considerably diminished, and has become insufficient to significantly enhance plant growth. When mycorrhizal fungi colonize the plant's root system, they create a network that increases the plant's capacity to absorb more water and nutrients such as phosphorus, copper and zinc.