u/Ancient_Inside7850

I don't see any pests on the underside if the leaves. Can anyone tell me what this might be and how to fix it?

Thank you!!

This is a determinate Better Bush tomato plant I purchased from a nursery on March 25th. In the last 2 weeks I have noticed branches from low to the middle of the plant turning yellow with dry brown patches. About 1 1/2 weeks ago I installed a drip irrigation system to help protect against fungal issues and to help with consistent soil moisture since I live in Florida. I have pruned some of the branches over the 2 week period, but since this is a determinate plant I know I can't keep doing that, especially since I think the plant may have reached full size. I have read about using a hydrogen peroxide spray and a baking soda/aspirin spray to treat blight, but I'm not sure if this blight or something else.

The last photo (if it appears in the order I uploaded the pics) is the day I transplanted it to the grow bag. It was super dense, lush, and healthy. I was tempted to prune it to facilitate air flow, but didn't due to the info I had read about this plant variety.

Any help is much appreciated!!

Thank you, fellow gardeners!! 🍅