I can’t be sure but I’m just going to go on the assumption that the yellow spots on the cucumber leaves are indeed downy mildew. And that means I need fungicide or I’ll watch my cucumber leaves die and the fruits will get scorched and, well it’s an all around bad thing.
I consulted Google once more, and came up with tons of information. I knew that I wanted to use something natural, organic, and safe around beneficial garden bugs, garden visitors, and people.
Turns out, hydrogen peroxide can be diluted and used as a fungicide for plants. I had no idea. I mixed up a solution of 1 part peroxide to 3 parts water and misted the tops and undersides of the leaves on all the cucumber plants.
I guess now I wait.