Control of Stem nematode Disease of Sweet Potato

Sweet potato stem nematode disease, commonly known as "bran heart disease".

(pathogenic nematode) Ditylenchus destrutor Thorne.

(host crop) sweet potato, potato, lily, ginseng, mint, angelica, etc.

(disease diagnosis) is mainly harmful to potato tubers, followed by stem vines. When the potato pieces were damaged, the potato meat was striped white or brown powder-like void, containing a large number of nematodes, so that the potato meat was dry, the weight was significantly reduced, and a hollow sound was made when it was hit with a hand bomb. The appearance of diseased potato is difficult to identify at the beginning of harvest, and the potato skin changes to pig liver color after storage. The damage of potato seedlings was mainly in the white part of the seedling base, with blue-purple massive or strip halo spots on the epidermis of the injured part, and brown dry rot in the pith in severe cases. Most of the stem vines appear yellowish-brown cracks on the upper epidermis of the base of the main vines near the ground, and then gradually turn brown, the pith shows white dry rot, and the seriously diseased stem vines become thicker and easy to break. The pathogenic nematode is potato stem nematode. Both female and male adults are worm-shaped, slender, slightly pointed at both ends and about 1 mm in length. The larvae are short and slender and the eggs are oval.

The pathogenic nematode overwinters in the cellar with eggs, larvae and adults in the harvested potato lumps, and the larvae and adults can also overwinter in soil and manure. Pathogenic nematodes are mainly transmitted by potato cubes and potato seedlings, and can be transmitted over a long distance. It can be carried and transmitted in the field by soil, manure, Rain Water, irrigation flow, people, animals and agricultural tools, as well as by raising seedlings with old seedbeds. The pathogenic nematode is tolerant to low temperature and can move at 2 ℃, and spawn and hatch when it is higher than 7 ℃. The optimum temperature for the activity is 25: 30 ℃. Like to move in moist, well-ventilated sandy soil.

(control measures) (1) select disease-resistant varieties, such as Lushu 7, Liaoshu 40, Beijing 553, Jishu 10 and so on. (2) to establish disease-free seed field and select disease-free seed potato or high-cut seedlings to prevent potato seedlings from carrying nematodes. (3) to apply rotten manure, do not use diseased potatoes and their dried potatoes and diseased seedlings as feed to prevent the spread of pathogenic nematodes into manure through the digestive tract of livestock. (4) rotation of grain crops, tobacco and cotton should be carried out for more than 3 years in seriously diseased areas, and the rotation of flood and drought is better. (5) do a good job of field sanitation, and when diseased plants are found in the field, they should be uprooted, buried or burned. After the harvest of the diseased field, the diseased body in the field should be thoroughly removed and the soil should be deeply turned over. (6) 5% Chuanxiling granules can be used for chemical control, 1-1.5 kg per 667 square meters, sprinkled on the base of potato seedlings, and then covered with soil and watered.