Symptoms: the type of potato virus disease is complex and the symptoms are mixed, usually mainly in the following types. Flower type. 1 normal leaf. It is generally more normal to grow and leaves are largely small, with only a slight or spot expression of the upper middle and upper leaves, which are rarely curled or flat. This type is very widely distributed and less harmful. Two heavy leaves. It's also called a scab leaf. The diseased blades are smaller and have black and brown nectar strips on their veins, leaf handles and troughs, so that the leaves appear to be plastered or dead, and the lower leaves of the post-plant are dried but not released, in the form of dying leaves. This type is more widely distributed and more harmful. Three wrinkled leaves. The strains are significantly constricted, the leaves are severely wrinkled, smaller, the flowers are severe, there are black and brown strips on the veins, leaves on the handles and the troughs, the tip of the leaves is bent down and the whole ball is embroidered. The disease falls, does not bloom and dies early in times of severe severity. This type, which is widely distributed and seriously hazardous, reduces production by 60 to 80 per cent, is the most important potato virus disease in china. Volkswagen. Sensible strains are convoluted upwards on the edges of the blades, with a middle vein, convoluted in a cylindrical form when the disease is severe, the blades are hard and brittle, some of the leaves are red or purple on their backs, the handles and truncheons are born with sharp horns, and the tube is bound to black and brown, and the chips are small. China is widely distributed, with a general reduction of 30 to 40 per cent, and is one of the main types of chinese potato virus disease. The beam top type. The disease is carried with its horns, bound up upwards, the leaves are smaller, the scrolls are condensed in semi-closed form, the whole of the luminous green and some of the top leaves of the plant are purple. The chips grow longer, the buds burst, the buds are prominent and sometimes the skins are lacerated。
