Harmful symptoms Sweet potato stem nematode disease, commonly known as "heart disease", "hollow disease", "empty scorpion", is a dangerous and devastating disease . It is mainly harmful to potato chips, followed by potato seedlings and potato vines. It can also cause rotten cockroaches during the storage period and cause bad beds during seedlings. Generally, it has no obvious effect on the elongation of potato vines and the development of potato stalks. The symptoms of diseased potatoes are divided into heart-shaped and split-skin types. 1, the heart type. From the disease of potato seedlings and seed potatoes, the disease develops from the top of the potato block to the lower part or the surrounding area. First, the inside of the longitudinal section of the root has a cotton-like white ramp, and later forms a brown ramp. The masses call it "heart" and "ç³ ç“¤". . Although the inside of this potato block has been destroyed, there is no change in appearance, but the weight is greatly reduced, and the finger is used to make a sound. 2, split skin type. The nematode pierces the outer epidermis with a needle and enters the internal damage of the root. The initial symptoms are not easy to see by the naked eye. The skin begins to fade, and soon becomes green. Some are slightly sunken, some have small cracks, and the subcutaneous tissue becomes brown and soft. Control technology Sweet potato stem nematodes are endoparasites, the insects are not neat, the transmission route is many, and the survival period is long. Therefore, there are many links in prevention and control, which must be deducted one by one, and can be eliminated after years of prevention and control. 1. Strengthen quarantine, do not adjust the potato from the ward to buy seedlings, and strictly quarantine the potato seedlings transferred into and out. 2. Establish a disease-free planting field, select a field that has not been planted with sweet potato for many years, or a disease-free land, apply a disease-free fertilizer that does not contain rotten potato pieces, disease and vines, water the disease-free water, and plant no healthy potato. Diseased seedlings. 3. Select resistant varieties. The selection of resistant varieties is a more economical and simple method. There is a big difference in resistance to stem nematode among sweet potato varieties. It is necessary to introduce and promote disease-resistant varieties suitable for local conditions. 4. Promote detoxification potatoes. Detoxification potato not only removes the virus, but also removes pathogens such as fungi, bacteria, and nematodes, making it a disease-free seedling. After planting, the seedlings are fast, the growth is strong, and the yield is high. 5. Covering the mulch film . Nematode disease is afraid of heat, and cultivation of sweet potato covered with plastic film can increase the temperature and play a role in killing nematodes. 6, the rotation is down. The disease-free area will be replaced by 2-3 years of sweet potato. The ward should be rotated for 3-4 years with non-host crops such as corn, wheat, millet and cotton , but it cannot be rotated with potato and bean crops. 7. Cultivate disease-free and strong seedlings. On the basis of the selection of disease-free seed potatoes, the seedlings were soaked in warm water at 50 ° C - 55 ° C for 10 minutes to kill the nematodes at 7 mm deep under the epidermis of the seed potatoes. Due to the high number of stem nematodes at the base of the seedlings, high seedlings can be used for planting the seedlings, and then the base of the seedlings is immersed in the base of the seedlings with 40% methyl isoflavin 200 times for 30 minutes. 8, Daejeon chemical control. In the severely ill areas , the stem nematodes in the soil are infested against disease-free seedlings, and they must be applied at the time of sowing. In the severely ill area, 40 kg of methyl isoflavone emulsifiable concentrate or 50% phoxim 2000-2500 times was used to pour 0.5 kg per hole. In the light ward area, high shearing seedlings can be used, and then the base of the sweet potato seedlings is immersed for 30 minutes with 40% methyl isoflavone emulsifiable concentrate or 50% phoxim emulsifiable concentrate 150-200 times. 9, clean the countryside. After the harvest, the diseased potato pieces and diseased vines are concentrated in the ground to be burned, and the weeds on the ground are removed in time. It is strictly forbidden to use diseased potatoes and sick vines. To make fertilizer, it needs to be fermented at a temperature above 50 °C. Half Shell Mussel,Frozen Cooked Half Shell Mussel,Seafood Frozen Half Shell Mussel,Frozen Half Shell Mussel Shengsi Huali Aquatic Products Co.,Ltd , https://www.mytilus-edulis.com