Powdery mildew resembles a light dusting of flour on top of the leaves of the vegetable plant, it is actually caused by a fungus that is airborne. It can occur on just about any vegetable, even some fruits such as sage, tomatoes, beans, watermelons, honeydew, pumpkins and marrows
What to do?
Normal milk will actually control powdery mildew and contains a natural foliar fertilizer, boosting the plant’s immune system in the process. A mixture of at least 10% milk mixed with 90% water will significantly reduce the severity of powdery mildew when sprayed weekly on the infected plant.