My tomato plants have yellowing leaves with brown spots. What is causing this and how can I fix it?

A: When the lower leaves of a tomato plant are yellowing around the edges with scattered brown spots, this is likely caused by early blight, a fungal disease.

Since the newer growth looks healthy, I recommend removing the lower leaves and tossing them in the trash (don’t compost them). Avoid overhead watering since this can spread the spores to new leaves. A weekly application of a copper-based fungicide can be helpful in preventing reappearance. Consider rotating your vegetable planting for next year’s garden.