A coast live oak, for example, will be more pest and disease ridden and have a significantly shortened life span, if there IS plentiful water and fertilizer but no mycorrhizae. There are several different types of fungi that take part in mycorrhizae. Two major groups are recognized. Found on most stress-tolerant plants, such as willow, eucalyptus, birch, and oaks,and are common to the forests of the Pacific northwest. There are thousands of this type.
Acid soils with good drainage favor ectomycorrhizae.
These fungi usually produce mushrooms above ground which produce spores. There are three main types. One is associated mainly with orchids. A second works in unison with the family Ericaceae which includes heather, manzanitas and rhododendron. They cannot be seen without a microscope.