Potato early blight and late blight are both diseases caused by fungi. It mainly affects leaves and potato chips, and cases of late blight can also harm stems. The difference is as follows: (1) On the leaf, the lesion of early blight is dark brown, round or nearly round, with concentric wheel lines. When the humidity is high, the black mold layer is produced on the diseased spot, and when the condition is serious, the leaves dry and fall off; The diseased leaves of late blight first grow soaked green-brown spots from the tip edge, and there are light green halo around the diseased spots. When the humidity is high, they quickly expand and turn brown, producing a thin layer of white mold, which makes the dry spots brown, dry and easy to crack, which is different from early blight.

2) On the stem: Early blight rarely has diseased spots or no diseased spots on the stem, but late blight can infect the petiole with brown stripes. When the disease is serious, the leaves droop and shrink, which eventually leads to black rot of the whole plant, and the whole field is scorched and gives off a rotten smell.

(3) On tubers: Early blight produces brown round or nearly round slightly depressed lesions on tubers with clear edges and light brown spongy dry rot under the skin; However, the late blight is different from the early blight, which produces brown or purple-brown large diseased spots on the tuber, and the flesh under the diseased spots is brown, spreading or rotting around.