1, late blight

Late blight can occur on leaves, petioles, stems and tubers. Leaf disease occurs in the leaf tip or leaf edge, producing round or semicircular dark green or dark brown spots, the edge is not obvious. When the air humidity is high, the spots expand rapidly and can extend to more than half of the leaves or even the whole leaf, and can invade the petiole and stem along the leaf veins, forming brown spots, causing the leaves to wither. And sagging, and finally the whole plant becomes scorched black wet rot. The edge of the spot has a ring of white mold. Potato blocks are easy to develop, forming light brown or gray-purple irregular lesions, lesions slightly sunken. The potato flesh under the spot becomes brown, and the diseased potato is easily infected with other rotting bacteria and soft rot.

2, virus disease

(1) foliar type: general plant development is normal, the leaves are basically unchanged and small. Only the middle and upper leaves appear slight flowers or spots, the leaves are rarely curled or jagged. This type is widely distributed and less harmful.?

(2) Hobble type. Disease-affected plants are dwarfed, leaf margins curled upward with the midvein as the center, rolled into a cylindrical shape when the disease is severe, leaves are hard and brittle, part of the back of the leaf blade is red or purplish-red, petioles and stems are at an acute angle, the vascular bundles are dark brown, and the potato pieces are small and dense. It is widely distributed in China, and generally reduces production by 30% to 40%. It is one of the main types of potato virus disease in China.?

(3) beam top type. Diseased plant petiole and stem at an acute angle, upward binding, leaf blade becomes smaller, often curled half closed, the whole plant dark green, some plants top leaves purple-red. Tuber becomes long, bud eyes protruding, bud eyebrow protruding, sometimes the epidermis has longitudinal crack.

3, ring rot?

(1) Wilt type. Initially, the top compound leaves begin to wilt, the leaf margins are slightly rolled, seemingly dehydrated, and expand downward. The leaves of the whole plant begin to fade green, curl and droop, and eventually the whole plant dies, but the leaves do not fall off.?

(2) Dry spot type. The disease first occurs at the top of compound leaves at the base of the plant, with green leaf tips, margins and veins, yellowish-green or grayish-green leaf flesh with obvious mottling, and dry or inward rolling leaf tips. After the appearance of dead spots on the top leaflets, other leaflets gradually appear dead spots. The disease gradually spreads upwards, and eventually the whole plant dies. The vascular bundles are visible at the base of the diseased stem turning dark brown.