There is published research with small pH electrodes showing that plants and mycorrhizal fungi can modify the pH of their root environment. Therefore, the bulk soil may be outside the preferred pH range, but the mycorrhizal fungi can surround the roots with a more tolerable pH environment.

Can you use too much mycorrhizae?

What happens if too much of a MYKE product is used on a plant? ... To survive, mycorrhizal fungi must colonize a plant's root system and develop a symbiotic relationship with the plant. As the excess fungi wouldn't have access to the root system, they would simply die without harming the plant in any way.

How do you permanently lower pH in soil?

Soil pH can be reduced most effectively by adding elemental sulfur, aluminum sulfate or sulfuric acid. The choice of which material to use depends on how fast you hope the pH will change and the type/size of plant experiencing the deficiency.