Occurrence and Control of Potato Black Shank Disease in Heilongjiang Province

Black shank disease occurs to varying degrees in various potato producing areas, with a mild incidence of 2%-5% and a serious incidence of 40%-50%, which often causes seedling breakage and seed potato rot in the field. In recent years, the harm of the disease in our province has a trend of increasing year by year, which greatly reduces the quality, yield and commercial potato rate of potato. In order to effectively prevent the disease, we must accurately identify its symptoms, clearly understand the law of the disease, and skillfully master the technology of comprehensive prevention and treatment.

1 symptom recognition

1.1 symptoms of black shank disease can occur during the whole growth period, mainly harmful to stems and tubers.

The main results were as follows: (1) the symptoms of aboveground infection were easy to be infected when the plant was high 15~18cm, at the same time, the leaves faded and yellow flowers rolled up, the plant internodes were shortened and the growth potential was weakened. The diseased plant is easy to pull out from the soil, the stem blackens and often cracks automatically and secretes foul-smelling mucus, and the base of the stem often contains rotten sweet potato, which eventually leads to plant wilting and death. When the disease occurs, brown vascular bundles can be seen in the cross section of the stem. When the disease developed slowly, the plant gradually withered, the tuber position moved upward, and it was easy to form aerial tubers.

(2) symptoms of underground infection: when seed A potato is infected, it gradually rotten in the soil without germination or just germination, resulting in lack of seedlings and broken strips; B, when tubers are infected, they radiate from the navel to the medulla, and the disease site is dark brown or black, and the vascular bundles are dark brown or short line-shaped by cross-section. squeeze the flesh by hand without separation, and when the disease is serious, the potato rotts into a cavity in the middle.

1.2 the cause of the disease is caused by the infection of carrot soft rot Eucalyptus black shank disease. This bacterium belongs to a low-temperature bacteria of the genus Orbsiella that causes soft rot and is not resistant to sunlight and dryness. Most of them die after exposure to the sun for 2 hours.

During ① cellar storage, poor ventilation, high temperature and humidity are conducive to the reproduction and harm of bacteria, often resulting in a large number of rotten potatoes, ② seed potato cutters are not sterilized, and then stacked together after cutting, which is not conducive to the rapid formation of cork layer in the cut wound, which increases the incidence rate. Because of the low soil temperature and the slow growth of plants in the land with heavy soil viscosity and poor drainage, ⑧ is not conducive to the formation of host cork layer and reduces the ability of anti-invasion; at the same time, because of the large soil water content, it is conducive to the reproduction, spread and invasion of bacteria, so the disease is serious.

2 infection pathway

Potato black shank disease is mainly carried by diseased tissues and spread through wounds and other infections. There are two ways of transmission: one is that the diseased tissue remains directly in the field. Some symptoms of potato black shank disease are not easy to be observed with the naked eye in the field, but they also lead to infection and yield reduction, mainly because the pathogen is still alive before the diseased tissue decays. In the field, bacteria invade from the wound through irrigation water, Rain Water, steam fog, machinery, weeds or insect vectors, infect the buds of tubers along the vascular bundles, and then invade the roots, stems, stolons and new tubers with the growth of the plant. and spread around along the vascular bundle, invading the intercellular space of the nearby parenchyma and secreting Pectinase to dissolve the middle gel layer of the cell wall, making the cells segregate, disintegrate and rot. Second, the diseased organization enters the farm manure through various channels and then applies it to the field.

3Comprehensive prevention and control.

According to the infection route of potato black shank, two main control methods were summarized: biological control and chemical control.

3.1 Biological control

3.2 Chemical control

(1) planting disease-free seed potato, reasonable rotation and whole potato sowing

(2) avoid potato litter and root tissue residue in the field, avoid applying farm manure with potato residue in the field, and use farm manure with potato residue after maturity, which is very important for the prevention and control of the disease.

(3) selection of disease-resistant varieties, such as disease resistance No. 1, etc.

(4) Black shank is one of the main diseases causing rotten cellar. Therefore, do a good job of cellar storage is a problem that can not be ignored.

3.2.1 Medicament treatment: (1) soak the cutter with 5% carbolic acid or 5% salt in boiling water and then cut into pieces; (2) disinfect the cutter with 0.1% mercury or 75% alcohol or 0.1% streptomycin sulfate, and then cut into pieces; (3) air the cut potato pieces in time to make the cut cork as soon as possible before sowing; or sow the potato pieces after sowing with plant ash, calcium peroxide, etc. Or soak the seeds with streptomycin sulfate of 500ppm, dry them and sow them.

3.2.2 in the field, the diseased plants were pulled out in time, and the diseased plants were sprayed at the same time to prevent the spread of the disease. If diseased plants are found in the field, dig up and destroy them in time, sprinkle a little hydrated lime on and around the diseased hole, and spray 4000 times of 72% streptomycin soluble powder or 25% complex ammonia copper solution or 50% copper succinate (DT) wettable powder or 95%CT fungicide water agent (copper acetate) 500 times or dimethylisone 500 times 1000 times, every 7 to 10 days, spray 2 times for 3 times. 1000ppm streptomycin sulfate can also be used to inject plants with mild disease, and each plant is injected with 3~4ml.