Well, I was thinking you must be on the east coast with that much pest and disease pressure!!!
The brown rot is easier to control with synthetic. Bonide has a product called Bonide Infuse. That should work. Read the label and follow it re. when to spray and how often.
Some of us use another product called Indar but you need someone to split it with a few others as it comes in a gallon size and costly. Also, if you have only one peach tree. you don’t need to invest that much money.
For pests, major pests for peaches are plum curcuilo, Oriental Fruit Moths, coddling moths and stink bugs. One organic approach is deterrence by using Surround, kaolin clay, spray.
Read this : First time using surround.
There are chemicals that are more effective. I do not use it so others who use it can give you advice.
@speedster1 is in Virginia. @scottfsmith is in Maryland. There are several who are in mid Atlantic states who could give you advice.