In order to provide an effective reply, you will need to know which fungal organism you are dealing with. I suggest your contact your local county extension office for a much more local approach. Contacting more than one certified Arborist to get a consensus of the problem could also prove helpful. Fungicides are typically applied as a preventative and complete treatment may also involve steps to correct plant health too. Some fungal diseases will require more than one treatment a season and sanitation practices as well.
