Leaf symptoms can be large tan to brown spots with concentric ridges or rings (target spots) and a broader lemon yellow margin or border. Generally, these lesions do not cross large veins on the leaf.
Early Blight generally starts in the lower canopy on olders leaves as they begin to die off. Young lesions are small tan to brown spots that form concentric rings as they mature. Several smaller lesions can coalesce, forming larger legions with numerous centers.
Early blight can also infect petioles and stems of potato. Generally, there is less evidence of concentric rings in petiole and stem infections.