Potato spindle tuber disease

(English name of virus) Potatospindletuberviroid

(host crop) potatoes, tomatoes, etc.

(disease diagnosis) the stems of diseased plants are erect and have few branches. When the leaf is lifted up, the angle between petiole and stem becomes smaller; the leaf edge is wavy or curled upward, the leaf is stiff and brittle, and the leaf color is dark green; the leaf becomes smaller and curls in a semi-closed twisted shape. In the budding stage, the plant growth was obviously slow, the leaf color became lighter, sometimes yellowed, and the seriously diseased plants were dwarfed. Tubers elongate, or one end is pointed, spindle-shaped, some pear-shaped or deformed; bud eyes increase, shallow, sometimes protruding, bud eyebrows protruding. The patients with red and purple skin disease fade, and their epidermis is smoother than healthy potato, sometimes cracked. Brown spots appeared near the bud eyes of some varieties, and tumors appeared on some tubers, showing deformities. The pathogenic virus is potato spindle tuber viroid. The virion is a tiny RNA molecule that is circular and has no protein shell. The passivation temperature was 65-80 ℃, the dilution end point was 0.001-0.0001, and the in vitro survival time was 3-5 days.

The virus is carried by seed potatoes and then transmitted or transmitted by juices, insects and seeds. Mainly mechanical transmission, mainly man-made transmission such as tuber section contact, knife transmission; field transmission by aphids, stink bugs, leaf beetles, etc.; the virus-carrying rate of seeds collected by plants is about 6% and 89%. The seeds with virus germinate slowly, the seedlings grow slowly, and the plants are yellowed, dwarfed, and even fascicled. Sowing poisonous seed potatoes and growing poisonous plants will speed up the spread of insects and aggravate the damage. High temperature is beneficial to viroid reproduction, aphid reproduction and activity, is not conducive to the growth resistance of potato, and is easy to cause disease occurrence and epidemic. On the contrary, the disease is lighter in the years and regions with large temperature difference. The virus-carrying rate of seed potato is related to the number of diseased plants in the early stage of the field and affects the severity of the disease. There were significant differences in disease resistance among potato varieties.

(control measures) (1) selection of disease-resistant varieties. The more resistant varieties are Dongnong 303, which can be selected appropriately according to the situation. (2) non-toxic seed potato was used. In order to establish a disease-free field, the referenced seed potato should be tested and confirmed to be non-toxic. (3) reduce man-made transmission. Adopt the way of direct seeding of whole potato to avoid the link of virus transmission by cutting and reduce mechanical transmission; during field farming operation, avoid damage contact between plants or leaves caused by tools and spread virus. (4) carry out knife disinfection. When cutting seed potatoes, the cutters (and tools) used are soaked or disinfected with 0.25% sodium hypochlorite solution or 1.0% calcium hypochlorite solution at any time to reduce infection. (5) timely control of aphids and disease prevention. Refer to other viral diseases. (6) strengthen cultivation management. Fine soil preparation, suitable sowing, high ridge cultivation, adequate fertilizer and water, avoiding potato formation under high temperature, increasing application of phosphorus and potassium fertilizer, etc., slow down the disease.