Sweetpotato black spot, also known as sweetpotato black shank, has become one of the most common and serious diseases in sweetpotato production areas in China. According to statistics, China's annual output loss caused by the disease is 5% to 10%. Diseased potatoes can also cause poisoning and serious deaths.
First, the symptoms of seedling stage, growth period and storage period can occur, the main harm potato, potato, does not harm the green part. The lesions on the tubers during storage are mostly found on the wounds and roots. They are black dots at the beginning and gradually expand into round, oval or irregular plaster-like lesions. They are slightly sunken and vary in diameter from 1 to 5 cm. , clear outline. Disease organization is hard, can be 2 to 3 mm deep potato meat, potato meat was dark green, bitter. In the late period of storage, it is often associated with other fungi and bacterial diseases, causing decay.
Second, comprehensive prevention and control strategies should be based on the disease-free seed potato, cultivation of disease-free and strong seedlings as the center, safe storage as a guarantee, and pharmaceutical control as an auxiliary comprehensive prevention and control measures.
1. Strictly implement the quarantine system. It is forbidden to transfer seeds and seedlings from the ward.
2. Use disease-free seed potatoes. The following methods and methods can be used to obtain disease-free seed potatoes.
(1) Disease-free farmland. Requires seedlings, soil, and manure to be free from bacteria, and to prevent the introduction of pathogens into agricultural operations. Therefore, it must be done: 1 using high-cutting seedlings, combined with the impregnation of seedlings, or in the spring potato vines cut into the planting summer potato. 2 Replanted land to be selected for 3 years without planting sweet potato habitat. 3 Seed potatoes harvested at the planting site must be harvested, transported, and stored individually. The transport vehicles and storage sheds should be harvested without bacteria, and they can be disinfected when necessary. 4 Note that manure does not carry bacteria.
(2) Select seed potatoes. After the seed potatoes are harvested, the diseased, injured, and frozen potato pieces must be strictly removed before the seedlings are planted.
(3) Safe storage. Seeds should be harvested at the right time, and frostbite should be strictly prevented. After the seed potatoes are put into the cellar, they are subjected to high temperature treatment, 35 to 37°C for 4 days and nights, and the relative humidity is kept at 90% so as to promote wound healing and prevent bacterial infection.
3. Cultivate disease-free strong seedlings.
(1) Sterilization of seed potatoes. The implementation of seed potato disinfection, remove the pathogens, methods are: 1 Wen Tang soaking seeds: potato chips pre-soaked in warm water at 40 °C ~ 50 °C 1 ~ 2 minutes, transferred to 50 °C ~ 54 °C warm water soaking for 10 minutes, water temperature and processing The time must be strictly controlled, pay attention to the upper and lower water temperature should be the same, the germination test should be carried out on the new varieties after treatment. Immediately after soaking, the seeds should be planted on the bed and the seedbed temperature should not be lower than 20°C. 2 Seed soaking: The seed potato can be treated with 45% doxamine, 70% thiophanate-methyl WP, and 88% ethyl allicin (402 antibacterial agent).
(2) Try to use a new seedbed to raise seedlings. When using the old seedbed, all old soil should be removed and sprayed for disinfection. Apply sterile fertilizer. In the early stage of raising seedlings, seed potatoes can be treated with high temperature to promote the formation of callus formation and prevent the invasion of bacteria from the wound. The high-temperature treatment is carried out after the seed potato is raised and maintained at a temperature of 34°C to 38°C, and then lowered to about 30°C, and then dropped to 25°C to 28°C after budding. Can also be used intermittent high temperature (Donton water fire) breeding method, that seed potatoes before bed, one foot pouring water. After the seed potatoes went to bed, the temperature was rapidly raised to 34°C to 38°C for 4 days, and then the temperature was maintained at 28°C to 30°C. Before sprouting, cool down to 20 °C ~ 22 °C. After each time, the seedlings are poured once and the water is heated to 28°C to 30°C. Implement high-cutting seedlings to obtain potato seedlings that do not contain bacteria or carry little bacteria. Spring potato seedlings on seedbeds (plants) require cuttings to be planted at 3 to 6 cm from the ground. The harvested seedlings were planted again in a place with good water and fertilizer conditions, and the management of fertilizers and water was strengthened. Then, they were cut at a height of 10 to 15 cm from the ground and planted in the field. This was a secondary high cutting seedling. In some places, picking yam and picking yam from summer potato fields is also a kind of disease prevention measure for high-cutting seedlings. During the seedling raising process, black spot can be controlled by the spray method of the medicament and the dipping method of the medicament. The agents are: 70% or 50% thiophanate-methyl WP. When dipping seedlings, it is required that the liquid be soaked to about 10 cm at the base of the seedlings.
4. Select resistant varieties.
5. Strengthen cultivation management. Implementing crop rotations, adding organic fertilizer without diseased residues, and preventing underground pests in time.
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