If you want to make it hard for fungus to grow on a peach tree it’s best to set up some kind of canopy over your tree during spring and until flowers are gone. This will keep the tree warm and dry. It must be open in the sides so pollination can take place.
I have moved my peach tree to an east facing wall to delay flowering. Last year the peach tree was growing on a south facing wall which was warmer but the flowers were surprised by late frost. The tree has already put out buds:

I’ll be using the roof as part of the canopy and two planks for the structure:

One end of the plank has been dug down:

The upper end is fastened to the roof with iron and screws:

The peach tree has shoots going in towards the wall, which I’ll have to remove:

And now it can grow vertically closer to the wall:

This is the pruned tree:

It’s possible to stay inside the wooden frame:

I’ve mounted a plank horizontally to stabilize the construction:

It’s mounted with a couple of screws at each end:

Then I just need to mount some clear plastic between the planks to form the shield against storm and rain:

I’ve left a length of plastic at the bottom to be covered with dirt the help keep the plastic in place:

Uhm, nice and cosy, shielded from the rain :

Hmm, maybe the tree should have been fastened to the wall… But the plastic will only stay on until the flowers are gone, so it will be okay for this season: