It's a foliar disease. It looks like blight, but you'd have to post close-up pics of more leaves. It's not going to be good news, whatever it is.

Did you ever spray fungicide? Daconil is popular as a preventative.

Doesn't look like Blight to me, Usually yellow leaves with brown edges means water stress. Also Later in the season I think some leaf branches will just die off naturally, especially near the bottom of the plant.

I see no mulch and weed competition, so I would say water stress + the age of the plant. Clip off the yellow and dying leaves, Add some mulch and see if that helps.

For a home fungal spray, Add the following to a gallon of water. 2 Tbl Spoons Baking Soda, 2 Table Spoons Veg Oil, Few drops of Dishsoap. Spray on the tops and bottoms of the leaves and the stems of the plants.

CH

I didn't mulch this year, I suspect nutrient issues, used micronutrient solution but was not very accurate/consistent in its use. Don't want to spray Daconil all the time (it rubs me the wrong way). Thinking of removing the top 2 inches of soil at the end of season and next year using thick landscaping fabric and mulch to protect the leaves from splach infestation from the soil. I need to test my soil.