A few of my tomato plants have developed brown spots and yellowing, which
according to a book on tomato problems I have, appears to be Gray Leaf Spot
or Early Blight. It seems more like the former.

Anyway, they say to plant resistant varieties or rotate crops, but list
either as a disease to be treated with fungicide. What fungicide do you use
to treat this? Would it be chemical or natural?

Thanks.