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These are foliar diseases that attack tomatoes, and sometimes potatoes. The fungal pathogen for both the diseases overwinter in infected crop residues. Early blight is caused by the fungus, Alternaria solani, and septoria leaf spot is caused by Septoria lycopersici. They are very common during warm, and humid conditions. Early blight appears mainly on older leaves at the base of the plant as yellow spots which later turns into dark brown spots. It can attack also petioles, stems, and fruits. The attack on the fruit occurs mainly on the calyx end.

The septoria leaf spot symptoms on leaves first appear as water-soaked lesions on the lower leaves eventually developing into leaf spots, which are smaller, and numerous appearing on the upper leaf surfaces.

Commercial growers - rotate tomatoes with other vegetables every three years. Commercial/home gardeners - plant certified disease-free seeds or transplants, and plant disease-resistant tomato cultivars. Improve the fertility of the soil to encourage growth of vigorous plants. Use regular application of copper and other fungicides if recommended in your state.