Also for preventative sprays there are a number of potassium bicarbonate (baking soda) organic sprays on the market. They work by changing the pH. If you arent seeing problems you can use these as often as you want. Take a look at Serenade, Green Cure, and companion. Last year I used Mancozeb and sulfur until July 1st, and then switched to the organics. I am a home grower and plan to do the same this year. I have different varieties than you and I'm sure different climate as well.