Circular dark brown to black spots of various sizes appear on the leaves. The spots, about 1 cm in diameter, are readily recognized by the concentric rings, or zonations, from which the name target spot was derived. When these spots occur around the margin of a leaf, their symmetrical ring-like appearance is often lost in the uneven outline of the edge of the leaf. Early blight appears as black lesions, which subsequently enlarge and elongate on the stalks, branches, and fruit pedicels, sometimes girdling them. Unlike septoria leaf spot, the centre of the lesion remains dark. These enlarged lesions are referred to as collar rot when they occur on the stems.
Bacteria may also attack the stem at ground level. Irrespective of the causal organism, the disease appears as a canker, or rot, of the stem at or above the soil line . When the stalk becomes girdled, the plant wilts and dies.
