Sengyan, I just use baking soda to spray my roses, two tablespoons to roughly 3 gals of boiling water and one tablespoon of liquid soap. Works for me

Thank you Stanly for your reply. The reason I'm looking for potassium bicarbonate is because it is used in the Cornell Formula. The scientist who worked on the Cornell Formula found that potassium bicarb was the only chemical that was effective against fungal diseases. Sodium bicarb was not very effective.

Sengyan

Thanks for that Sengyan. I have a lot of roses so go through a lot of spray to keep them clean. If you hear from any one please post so we can share, I would be very interested