What is the reason fungal diseases have been able to evolve and spread rapidly?

The reason that fungal diseases have been evolved and will keep on evolving is the global rise in temperature.

Researches have found that earlier there was a difference in the temperature of the human body and environment.

There was a temperature difference in the temperature of the body and environment because body had high temperature inside body that helped in providing tolerance against  fungal infection.

But due to high temperature in the environment there is no significant difference in the body's temperature and environmental temperature, so body is more susceptible to fungal infections.  

it restores trees to areas where they once grew.