Zu viel des guten ?

Hello. To prevent Powdery Mildew the Gardening Collage Prof. said it's calcium uptake that helps prevent it, like bone meal (tip for next year). For now: half an once of Apple Cider Vinegar (with 5% acetic acid) in a 1 liter spray bottle and spray plants. You can make it a little stronger but it might burn the plants. Something different: 1 part milk to 9 parts water. Do not spray in the sun light and let it dry before it gets a lot of sun. The dried milk reacts with the sunlight to have a antiseptic effect. Please look this up on google before you start, and there is more there too. Good Luck. Chuck.