It looks like your tomato plants may have Early blight (Alternaria spp.), the most common fungal disease of tomatoes in Kentucky. It appears on leaves and stems as dark brown lesions with concentric rings. Older leaves are usually affected first, but the disease spreads upward to newer growth
under favorable conditions. Lesions enlarge and coalesce; extensive blighting (sudden death) and loss of leaves can result. Lesions may develop near the stem end of fruit during severe outbreaks. Fruit lesions become sunken and leathery; a thick mass of black spores may be present under humid or wet conditions.

Management:

• Promptly remove and destroy diseased plant material
• Manage weeds and potential alternative hosts
• Avoid wetting fruit and leaves when irrigating
• Apply protectant fungicides
• Rotate with non-host crops
• Promptly destroy crop residues after harvest
• Deep plow to bury residual inoculum

I recommend that you download the "SOW" app, a gardening guide that is largely based on ID-128 publication "Home Vegetable Gardening in Kentucky" from the U.K. Cooperative Extension Service.

Let me know if you have any questions.