Green Cure, which is made for PM and other plant fungus is 100% pure potassium bicarb. I've used it before with good results.
with all due respect, you are mistaken.
http://www.megagro.com/pdf/GreenCureMSDS.pdf
2. COMPOSITION/INFORMATION ON INGREDIENTS Ingredients % by Weight CAS Number
Potassium Bicarbonate 85% 298-14-6
Contains no components that are reported to be carcinogenic by any reference source
including IARC, OSHA, NTP, and ACGIH.