How can I stop yellow spots from spreading on tomato leaves?

[Robert51]

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

[Michael.R]

That sounds rough your tomato leaves turning yellow and spreading fast could just be a stress or a disease on the plant Lower leaves often show problems first.

[Patrick90]

In my garden early blight showed up as yellow spots that spread I pruned infected leaves and boosted airflow which slowed the spread.

[SavannahJM]

Not sure what it is could be a magnesium deficiency or a disease the quick spread makes me lean toward disease but more checks would help

[EleanorPG]

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