some have mine did this last year and I think it was sun scorch. the plants grew away and fruited ok.

Hi, I agree with Seaburngirl, the lower leaves will die off anyway, so you can cut them off if you wish, when you water them, try to just water the soil, avoiding the leaves as much as possible, even when the plants get bigger, and to help pollination, tap the cane supports as you pass by, very gently, Derek.

I just want to suggest that you heavily mulch your tomato plants. Mulching has a number of benefits; it reduces water loss, keeps the plants evenly moist, creates a habitat for earthworms - cool, dark, moist. keeps roots cool, creates a protective barrier which prevents pathogens & spores from splashing up onto your plants.