My tomato plants are starting to display yellow leaves with dark brown spots near the bottom of the plants. On a few plants this seems to be spreading to the leaves immediately above the affected leaves. What can I do?
If you have noticed tomato leaf spots and the lower leaves turning yellow, you may have tomato early blight alternaria. This tomato disease causes damage to the leaves, stems and even the fruit of the plant. Once a plant is infected tomato early blight alternaria, a fungicide can be sprayed on the plant. This can help reduce the damage from the plant, but frequently this will only lessen, not eliminate the problem. The best way how to treat leaf spot on tomatoes is to make sure it doesn’t occur in the first place. For future plantings, make sure the tomato plants are far enough apart. Also, don’t water the plants from overhead; use drip irrigation instead or water from the plant bottom. If you find Alternaria Alternata in your garden, make sure not to plant any other plants from the nightshade family in that spot for at least a full year. Destroy any tomatoes that have tomato leaf spots. Do not compost tomato plants with plant leaf spots, as this can re-infest your garden next year with tomato early blight alternaria.