My cherry tomato has leaves on the inside and the bottom that are yellowing, and then turning brown. Sometimes they do this all at once, and then sometime from the tip in. There are no spots, and no "target" pattern. I have searched through TAMU's pics and see nothing exactly like except the pictures of verticillum wilt, but the fruit isn't stunted and it seems unlikely in a Husky Red Cherry.
How likely is it that this is a fungal disease vs. leaf age? I water by hand, so the only times the leaves are wet is when it rains.
Should I treat with a organic fungicide as a "just in case" manuever, or leave it alone? I am religious about checking the water level, so I don't think it's stress. The plant is huge..almost five feet tall and four feet wide. It's getting new stakes this weekend. It gets seaweed extract spray once a week and cornmeal once a month, and compost as it requires. Only thing it's been sprayed with is BT (I had a bumper crop of hornworms.).