Milk as a fungicide

A week ago I sprayed my Oak trees with a dilute solution ( about 1 : 8 ) of skim milk to try to treat the very heavy powdery mildew which had infected them all. It was killing off all the new growth coming through in the late summer.

After waiting a week to see what happened I had a look at my Oak leaves which were sprayed as an attempt to treat the heavy powdery mildew. I am so extremely surprised at how effective this has been. The underlying damage to the leaves is obviously still there - but the mildew is almost entirely gone.

This should extend my growing season a little and improve the vigour of the oaks greatly. 

This is a great treatment. I cant see any downsides.