Oxidate 2.0 at 15ml/gal..is pretty expensive..but depending on the size of your grow could be worth the expense.
Horsetail Tea is very cheap in bulk. This recipe can be halved for a smaller amount. Boil 4 cups of water..once water is boiling pour 1 oz (about 3/4 of a beer cup) of HT into the pot..put on the lid..turn the heat down to medium and let steep for 20 minutes. Strain over a fine metal strainer into a gallon pitcher and add enough water to make one full gallon. That should bring the temps down cool enough to spray immediately. Soak plants. If you have leftovers you can refigerate for up to a few days. If you see PM forming spray 3 days in a row..and spray once per week after as maintenance. Can be used up to harvest without any ill effects, except it may turn a few hairs depending on how late in flower you spray. HT is nothing short of amazing and I've been preaching it's use for a long time. It beats the pants of of things like horticultural oil, neem,
green cleaner, etc. It can even be added as a soil drench to increase silica content.
IME most plants will recover even from a bad infection, but some plants are just too sick or weakened to fully recover from PM and you will see it try to make a comeback in the central cola parts. Ditch them if you have to. Sometimes good sulfur burning is enough..really depends on plant immunity..environment and strain of PM. Stay dilligent and you will be successful.