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Occasionally fungicidal sprays can burn and damage your plant leaves. Test each type of spray on a small area of your plant, such as 1 low leaf, before spraying your whole plant. Spray the leaf with enough spray that it runs off the leaf, and allow it to dry. If the leaf begins turning yellow or brown, this spray may be too harsh for this plant. Try different types of sprays on different leaves until you find a couple that work. Mildew can be a stubborn fungus that adapts and builds resistance to things that fight it. When you've found a couple sprays that work, alternate them so that the mildew doesn't build a resistance to any of them. For example, use a baking soda spray 1 week and a milk spray or vinegar spray the next. When you begin a spray treatment regimen for powdery mildew, you will want to spray your infected plant in the morning to allow the sun to dry the treatment on the leaves. You may often see improvement after 1 treatment. Wait at least a week to apply another spray treatment, and do this only if you do not see improvement on your leaves from the first treatment. Before spraying your infected leaves, wipe them with a clean, dry cloth to get some of the mildew off first. This helps reduce the amount of mildew that runs off into the soil with your spray solution. Alternatively, rub infected leaves against each other to get some of the mildew off. Each time you use a homemade spray, spray each infected leaf generously enough that the spray starts to run off the leaf. Do not wipe the spray from the leaf, but allow the spray to run off and air dry. Chemical fungicides can be effective, but they can cause other problems with your garden as well. They can harm good organisms in the soil, as well as bees and other pollinating insects that are healthy for a thriving garden. They also can affect how safe it is to eat plants they are used on, so be sure to follow all packaging directions carefully if you're using them on edible plants. Since organic fungicides can be made easily at home, it's wise to try them first before resorting to chemical treatments.
Test each spray on your plant before using it. Alternate sprays so the mildew doesn't build resistance. Spray infected plant areas in the morning no more than once per week. Wipe leaves with a clean cloth to partially remove mildew. Allow spray to run off the leaves. Use chemical fungicides with caution.