What I did was add the Milk and Potassium Bicarbonate together with a bit of dish soap and sprayed every 3 days for 18 days then once a week then every 2. I even sprayed in mid-bloom with no ill effects.
My conclusion:
Adding the 2 together and more aggressive foliar spray treatments 100% worked.
So here is a nice cheap recipe to Cure and Deter Powdery Mildew.
Half a liter of hot/warm water add 3 teaspoons of Potassium Bicarbonate and mix well (allow to cool if using hot water).
Add half a liter of milk any type will do even if it has gone off.
To finish just add a squirt of dishwashing soap and mix well.
The outside Girl
The clones I took from the Outside girl ( These were treated through veg as prevention)
It worked for me and saved me from losing a strain I have had for many years.
Link to the Potassium Bicarbonate. https://www.amazon.co.uk/Intralabs-Pota ... C75&sr=1-1