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Early Blight And Septoria Leaf Spot

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. As spots enlarge, concentic brown rings are usually visible.  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 with tan to gray centers. The spots are smaller, and more numerous appearing on the upper leaf surfaces. Many numerous tiny black spots or pustules may be seen in the lighter inner tissue of the spots.


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. If needed, use fungicides according to directions recommended by your local Extension office.


early blight

early blight