Common leaf spot prevention on strawberries?

[Elizabeth C]

Has anyone found a natural way to kill common leaf spot on strawberry plants? The old leaves from last year had it quite a bit, and now it’s spreading to the new. I thought about spraying with water that has tea tree essential oil since tea tree is anti-fungal and the issue is fungal…

 

[YumYum]

I think copper fungicide is labeled for use on that but I haven't used it. I don't know if it is more of a preventative than a cure.