Potato is an important food crop in China. Diseases and insect pests are one of the important factors affecting its yield. In recent years, potato virus disease and late blight have become more serious. Bacterial wilt, locusts and other pests have also occurred from time to time. Prevention and control of potato pests and diseases should be based on prevention and adhere to comprehensive prevention and control. The third and sixth editions of the planting technology in this period focus on the identification and prevention and control of potato pests and diseases, and hope to help farmers.
Fungal diseases
Late blight
The potato late blight is widespread throughout the country and is seriously endangered. Late blight occurred in protected areas in the past, but in recent years, especially in rainy years, it can occur in all seasons. In severe cases, the leaves wilted and the whole plant died.
Symptoms: The diseased leaves initially presented with dark green lesions on the tips of the leaves and leaf margins. Under conditions conducive to disease such as moisture, the lesions rapidly expanded and showed irregular greenish-green lesions on the edges of the diseased leaves. Dry, dry, leaves on the edge of the lesion on the back can see the formation of the fungus layer of the downy mildew. When the disease is serious, the leaves are drooping and most of the leaves are dead and falling, leaving only a few green leaves on the top. In hot and dry conditions, the lesions stop expanding and form necrotic areas. The surface of infected tubers has brown spots. Gradually expand to form slightly dark dark brown irregular lesions. After the diseased potato was cut open, a layer of brownish dry tissue extending approximately 1 cm inward from the surface was observed. The diseased potato is often rotted with the infestation of secondary microorganisms under high temperature and humidity conditions.
Transmission route: Pathogens use hyphae to overwinter in storage tubers or discarded tubers. After sowing the following year, they invade stems and leaves with the growth of young shoots, and then form conidia (sporangia), which are transmitted by air or flowing water. After conidia have absorbed water, 6 to 12 zoospore can usually form. Zoospore can germinate from the leaf pores and invade the host. Conidia or zoospores may also infiltrate soil with rain or irrigation water and invade tubers from wounds or cutaneous holes. Late blight is most likely to be endangered when temperatures are around 20°C and humidity is high.
Control measures: 1. Select resistant varieties. 2. Use disease-free seed potatoes. 3. According to the incidence of local history, determine the application of pesticides before the onset of prevention, after every 2 to 3 weeks 1 to 2 times.
Verticillium wilt
Symptoms: This disease causes early infection of the plant. Leaves chlorotic, yellow and withered. The vascular bundle of the stem becomes light brown, sometimes with necrotic striations at the base of the stem. Tuber vascular bundles are light brown, irregular patches on the surface, pink or tan around the buds, and can cause hollows in tubers when severe.
Route of transmission: Contaminated soil, susceptible tubers, and susceptible weeds that adhere to tubers can be transmitted. Conidia can also be transmitted through air currents. The germs invade mainly through root hairs, wounds, shoots, and foliage. Control measures: 1. Select resistant varieties. 2. Rotate with grass or bean crops to avoid rotation with solanaceous crops. 3. Prevent diseased weeds such as dandelion and leeks.
The above are common bacterial and fungal diseases. They not only occur in production. If there is no good storage conditions, they are easy to infect pathogens. Therefore, they must pay attention to temperature and humidity during storage. Generally, the temperature is controlled at 0°C-4°C. The humidity should be 65% to 85%. The storage pit must be ventilated and ventilated to reduce the concentration of carbon dioxide, avoiding the temperature and humidity of the storage pit, affecting the physiological activity of the tiling, causing the germs to germinate, infecting, and causing the potato pieces to rot. .
Bacterial diseases
Black shank
Symptoms: The damaged plant usually starts from the decaying seed potato and spreads to the upper part of the stem. The black part of the stem is black and the vascular bundle is discolored. The growth was dwarfed and stiffened. The early victim leaves were chlorotic and the top leaves curled upward. Afterwards, the whole plant gradually withered and died. The late-stage plants showed tubers with different degrees of susceptibility, and the vascular bundles were darkened on the cross section of the diseased potato. The light only changes color in the umbilicus, and the heavy-duty potato block has turned black and rotted in the field and has an odor.
Route of transmission: The initial infection of the disease is mainly from the surface of the seed potatoes or the internal bacteria of the seed potatoes. After planting, the seed potatoes rot and release large amounts of bacteria into the soil. Bacteria have a short survival time in the soil and can move through soil and moisture over short distances and infect nearby host stems and developing potato. During the growing season, bacteria can accumulate in the rhizosphere of the host or some weeds. Bacteria in the soil after harvest
Wintering on diseased tubers during storage. Cuttings of seed potatoes and wounds caused by mechanical operations and insect damage are the main vectors.
Control measures: 1. Select disease-resistant varieties and strictly implement quarantine to prevent the introduction of diseased potatoes. 2. Choose sandy loam cultivation. 3. Can choose to sow with small whole potatoes, cut seed potatoes must be carefully selected before sowing, remove diseases, hurt potato pieces, and other types of healing after the next seed. 4. The diseased plants in the field should be excavated in time and lime be disinfected in the empty nests. Remove discarded potato pieces and plant debris from the field at the time of harvest.
Soft rot
Symptoms: Decayed tuber during late growth and storage.
Potato stems and stems and tubers can be infected through lenticels and wounds. There are dark brown spots on the plants. In severe cases, the stem marrow rots, forming a hollow and lodging, and the epidermis of the susceptible tuber is light brown, followed by soft rot and odor. Transmission route: Soft rot infection is similar to black shank disease. Pathogenic bacteria are most suitable for onset in hot and humid conditions. Bacteria can survive in soil for up to 3 years. Bacteria often spread through water-washed tuber wounds. Irregular tubers, injuries, sun exposure and other fungal infestations, warm, high humidity and lack of oxygen, and excessive nitrogen fertilizer application are all conducive to the infection of soft rot.
Control measures: 1. Strengthen the cultivator before harvest, pay attention to field drainage, in order to reduce the infection of lenticels. 2. Mature tubers should be protected from direct and mechanical damage during harvesting and shipment. Avoid direct sunlight, store them in a cool, dry, well-ventilated place. Do not rinse the tubers with water before storage.
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