Diseases and pests of sweet sorghum are one of the important factors affecting the development of sweet sorghum industry. In order to nip in the bud, the pests and potential pests of sweet sorghum are introduced as follows. 1 Disease 1. 1 Head smut mainly occurs in the ear, commonly known as "black rice". Generally speaking, the affected plants are short. The symptoms of the disease were obvious during the flag-raising period. The flag leaf is tightly wound on the diseased ear, and the middle part of the diseased ear bulges. In the initial stage, the leaves are peeled into filaments and wrapped in white bags. After heading, the upper white skin is reddish, and black powder is scattered after breaking, and then a group of residual filamentous vascular bundle tissues are exposed. Winter spores spread through soil and seeds. When the length of sweet sorghum seeds from tip to bud is 1 ~ 1.5 cm, it is the most suitable growth period for pathogen infection. Prevention and control methods: select and keep seeds in disease-free fields or less disease-free fields; Selecting disease-resistant varieties; Cut down the diseased plants in time when they are found, and cut down the diseased plants before the ash bag breaks, and pull them out of the ground for destruction. If sick ears are used to feed livestock or retting manure, the manure must be decomposed before it can be used to reduce the source of bacteria; After the seeds are screened and winnowed to remove impurities and particles, they are treated with chemicals; In order to reduce soil germs and their harm, the planting structure should be rotated for more than 3 years. 1.2 leaf anthracnose can occur from seedling stage to heading stage. At the beginning, brown spots appeared on the tip of the blade, then expanded into ellipse or merged into irregular spots, with purple-red or purple-black edges and light brown center. The small black spots on both sides of leaves are conidia, which will cause serious diseases when soil humidity and atmospheric humidity are high. When the disease occurs, the function of leaves decreases, which affects the yield of stems and grains. Prevention and treatment methods: remove the diseased plant residues, burn or bury them deeply; Soak the seeds with appropriate bactericide for disinfection, rinse and sow; Prevention and treatment with fungicides at the initial stage of the disease; Select disease-resistant varieties. 1.3 rust symptoms may appear at seedling stage, leading to summer spore accumulation. Spore heap edge purple, mostly on the back of leaves. Summer spores can infect plants again through air flow, showing pale yellow spots at first, and then gradually forming oval and slightly convex spots. After rupture, they emit rust-like reddish-brown and dark brown powders, namely summer spores and winter spores. Winter spores overwinter on the remains of diseased plants in the field. Too dense plants, poor drainage and partial application of nitrogen fertilizer will aggravate the disease. Prevention and control methods: clean up the remains of diseased plants in the field at the end of autumn to reduce the spread of pathogens; Timely topdressing nitrogen fertilizer, paying attention to drainage and waterlogging prevention during the growth period, and strengthening field management; At the beginning of the disease, control the field with chemical agents; Select disease-resistant varieties. 1.4 loose smut appeared after heading, and the affected plants headed later, shorter, thinner and had fewer nodes than healthy plants; The stamens and inner and outer glumes of each spikelet on the diseased ear turned into black powder due to injury, and there was a gray-white film outside, which turned into an oval gray bag and protruded from the glume shell. After the outer membrane was broken, the dark brown powdery chlamydospores scattered, revealing a long central axis, which was formed by the host tissue, and the glume of the diseased ear was slightly longer than that of the healthy ear. The disease is mainly transmitted by seeds. After the diseased seeds are sown, the pathogen germinates at the same time with the seeds, invades the host tissue, develops to the growing point, and finally invades the ear to form the diseased ear. Chemically treated head smut, diseased ears and chaff should be destroyed centrally to reduce the source of bacteria. 1.5 The leaf spot of Sorghum Great Blight is spindle-shaped, with light brown center and purple edge. In the early stage, irregular ring marks often appear, and the lesion is large, generally about 20 ~ 60× 4 ~ 10 mm, and black mold is produced on both sides of the lesion, that is, at the fruiting body of the pathogen. Usually it develops gradually from the lower part of the plant. Under humid conditions, the diseased spots developed rapidly and merged with each other, resulting in dry leaves. The disease occurred earlier and was seriously damaged in July, which was the main reason for the large area of sorghum straw returning to the field in normal temperature and rainy years. Control methods: select disease-resistant varieties; In autumn, plough in time, bury the diseased plants and residues in the soil, pay special attention to the indispensable fertilizer in the later growth stage of sorghum, and reduce diseases. There are many pests that do harm to sweet sorghum, mainly as follows: 2. 1 underground pest 2. 1. 1 mole cricket. In China, there are mainly African crickets and North China crickets, and North China crickets are mainly distributed in northern China. Long life history, 1 year or year, 1 generation. Staying in the daytime and coming out at night, it has strong phototaxis and likes sweet substances, which harms the root system of sweet sorghum and causes seedling death. Prevention and control methods: before or during sowing, apply pesticides in the planting ditch; Seed dressing with chemicals; In the sorghum field, dig a small pit every 20 meters or so, then put horse manure or fresh grass with water into the pit to lure insects in and concentrate on killing them during the day. Or put poison bait in the pit; You can dig nests to kill insects in spring and dig eggs in summer. 2. 1.2 grubs (scarabs) mainly include Korean scarabs and oriental scarabs. Its life history is long, adults or larvae overwinter in the soil, adults do it at sunrise or stay up at night, and the latter is mostly. Nocturnal species are often phototactic and usually have the habit of feign death. Damage to the roots of seedlings, resulting in lack of seedlings and broken strips. Prevention and control methods: apply appropriate amount of pesticides along each acre of planting ditch; Artificial killing or light trapping of adults; When applying fertilizer, fully decomposed manure must be used, otherwise grubs are easy to breed; It can be intercropped with castor, which can lure and poison many kinds of scarabs. Artificial lighting was used to trap and kill in the emergence stage; The use of bacterial insecticides to control grubs also has a certain effect, mainly using Bacillus japonicus. 2.2 The main pests in seedling stage are sorghum weevil, which concentrates on the stems of seedlings and sucks the juice of seedlings, which affects the growth of seedlings and even causes the death of seedlings. Prevention and control methods: when adults overwinter in groups, lift rocks and search for grass to catch overwintering larvae; Beauveria bassiana can be used for control when humidity is high. 2.3 Leaf-eating pests 2.3. 1 Aphids harm sweet sorghum, but sugarcane aphids are the most serious. High temperature, drought and little rain can occur in large quantities. This insect has a short generation and fast reproduction. It overwinters on the grass, hatches after the temperature reaches 65438 00℃ in spring, feeds on the grass roots, and then moves up to the tender stems to feed. After the second generation, parthenocarpy with wings and parthenocarpy without wings moved to sorghum in June and parasitized on the back of leaves to feed on nutrients. At the beginning, it mostly harmed the lower leaves, and gradually spread to the upper leaves of plants, so that the back of the leaves was covered with insects, and a large amount of honey dew was secreted, which dripped on the lower leaves and stems to make them shine, so it was called "oil plants", which affected the photosynthesis and normal growth of plants and made the leaves turn red and glow. Prevention and control methods: at the beginning, gently spread the leaves with aphids, take them out of the field and bury them deeply, which has a certain effect on controlling the spread of aphids; Chemical agents can be used for control, but it should be noted that some varieties are allergic to organophosphorus pesticides and should not be used; Soybean intercropping can also improve the microclimate in the field; In the year of large occurrence, low-volume spraying of pesticides can be used. 2.3.2 The boat moth occurred in North China 1 year 1 generation. The pupae overwinter at the depth of 6 ~ 10 cm, emerge in late June of the following year, and the adults bloom in mid-July. After mating, it lays eggs on the back of sorghum leaves, and the eggs are scattered. After hatching, the larvae feed on leaves, the damage period is about 65438 0 months, and they overwinter as pupae. Adults lie down during the day and come out at night. They have phototaxis, like humidity and darkness, and are often on the back of leaves. If it rains continuously in July and the climate is cool, it is easy to happen. Cohesive soil is heavier than sandy soil. Prevention and control methods: artificial capture of larvae. Moth larvae are large, inactive and easy to catch, and can be caught and killed according to the victim's shape; Digging pupae in wintering period or removing egg blocks in spawning period; Light trapping and killing. 2.3.3 The armyworm has no diapause during its growth and development, and can reproduce all year round under suitable conditions; Therefore, the generations in different regions of China are different with different regional latitudes, and the higher the latitude, the fewer the generations. Staying inside during the day and going out at night has a strong tendency of black light. It is a pest of Gramineae crops, and its larvae eat leaves and even ears. Prevention and control methods: from the early stage of adult oviposition, insert 150 millet grass into each hectare of wheat field to induce it to lay eggs, and replace 1 handful every two days, burn these millet grass, or collect eggs in the field when laying eggs; When adults occur, setting 1 sweet and sour wine traps every 0. 13 ~ 0.20 hectares or setting 30 ~ 45 poplar branches or straws every hectare can obviously reduce the number of eggs laid in the field and the density of larvae. Application of diflubenzuron and other chemicals to control natural enemies with little lethality. 2.4 borer 2.4. 1 corn borer corn borer is harmful to sorghum producing areas in northwest, north, northeast and east China. The generation of Ostrinia furnacalis varies with different climatic conditions, and it can occur 1 ~ 6 generations every year. Prevention and control methods: when corn borer harms the heart leaves, spray pesticides (used with caution for organophosphorus allergic varieties); At the peak of egg incubation, control the heart leaves with pesticides. 2.4.2 The insect has two generations in North China, Henan, Jiangsu and other provinces 1 year. Young larvae eat mesophyll in the heart leaves, leaving only the epidermis in the form of paper. With the increase of age, they bite into irregular holes or into the stems, and some bite out the growing points, which makes sorghum become dead and the stems easily break. Mature larvae overwinter in sorghum stalks, which mainly harms summer sowing sweet sorghum or its late-maturing varieties. Control method: similar to corn borer, if it happens at the same time, it can be controlled at the same time. If there is a time difference (more than 10 days), spray more 1 time; There are many overwintering larvae of Chilo suppressalis in the upper part of culm, so long pinching can be used to reduce overwintering larvae during harvesting. 2.5 Ear pest 2.5. 1 stem borer, which damages the seeds during the green rice period. The larvae eat the seeds, and after the 3rd instar, they climb out of the reticulated spikelets and walk through them, which harms the seeds. In severe cases, the whole ear can be eaten up, and the larva wormhole is full of feces, which is easy to cause mildew and reduce the quality of sorghum. 1 year, there are 2 ~ 3 generations in North China and 4 ~ 5 generations in the Yangtze River basin, and the last generation of mature larvae overwinters in the gap between sorghum, corn, castor and sunflower trays and warehouses. Adults have strong chemotaxis, and eclosion adults must be supplemented with nutrition to lay eggs. Control method: clear the overwintering insects in the overwintering place, and concentrate the overwintering insects on the rice stalks and ears during threshing. Overwintering larvae in the cracks of bark in warehouses and orchards should also be killed; The number of eggs and larvae of sorghum should be investigated at the beginning of heading, and chemical control should be carried out when the rate of insect (egg) plants reaches more than 20%. 2.5.2/kloc-0 has 2 ~ 3 generations per year, overwintering with overwintering larvae in stubble, and the overwintering larvae in northeast and northwest regions pupate in late May, and the damage period is from June to September. Generations overlap in the field, and the seedlings suffer 1 ~ 2 generations, resulting in heart failure and overwintering with overwintering larvae or pupae. Control methods: Rake the field in autumn, expose the stubble to the ground, and kill the overwintering larvae under the condition of low temperature drying; Manually remove dead seedlings and burn them centrally; Master the insect situation and carry out chemical control when necessary; Light trapping and killing. The above pests and diseases are only the main types of sweet sorghum. With the continuous expansion of planting area, new pests and diseases will continue to appear. According to the requirements of plant protection policy, comprehensive measures should be taken to control pests and diseases in order to protect the environment and minimize their harm. If we blindly pursue the high yield of sweet sorghum and destroy the environmental conditions on which human beings depend, it will not be worth the candle and get twice the result with half the effort!

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