downey mildew devastation

Mar 21, 2021
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I am starting my 3rd year gardening. Last year was very disappointing due to a downey mildew infestation that killed or seriously damaged my cinnamon basil, sweet basil, mint, catnip, and several other plants.

I tried to find a way to treat it. About halfway through the season I started using a fungicide mixture with these ingredients:

2 tbsp Dawn soap
2 tbsp canola oil
4 tbsp baking soda
1 gallon of water

The tips of almost every leaf turned black after treating. I guess they all had the fungus whether I could see it or not?

Over the winter I sprayed every place where I found the downey mildew down with the mixture above multiple times to try to kill any that might survive the winter.

Is there anything else I can do to prevent this horrible fungus from returning?

Here are some pictures of damaged/necrotized leaves, damaged and yellowing leaves on the sweet basil plant (notice the black tips), and a damaged vs. healthy cinnamon basil leaf.



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