Why are my tomato leaves turning yellow with spots, latest science news?

[Luke18]

My tomato plants have developed yellow spots on the leaves that are spreading quickly

[Jeffrey_S]

That sounds rough your tomato leaves turning yellow and spreading fast is usually disease or stress like overwatering or humidity.

[TylerH]

In my own garden I had early blight show up as yellow spots that spread; I pruned the worst leaves and improved airflow and it slowed.

[Donald66]

Could also be a nutrient issue like magnesium deficiency but the quick spread points to a pathogen most of the time.

[AbigailXM]

Best next moves: water at soil level, mulch to keep leaves dry, remove infected leaves, and consider a labeled fungicide if many plants are affected.