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(I) Main diseases of vegetables and their prevention and control (1) Vegetable downy mildew: It can damage cruciferous vegetables, cucumbers, lettuce, onions, spinach, and mandarin. Distribution and damage: Downy mildew is a relatively important and harmful disease. This type of disease symptoms, the law of occurrence, the biological characteristics of the pathogen and the environmental conditions of the disease are similar, causing serious illness in the epidemic loss. Symptoms: The disease can develop during the entire growth period. The leaves, stems, pedicels, and seed pods can all be infected by the pathogen. On the leaves, yellowish-green lesions with unknown edges were gradually developed and gradually turned yellow to brown. After the lesions were expanded, they were limited by the veins to become polygonal. When the humidity is high in the field, a layer of white frosty mildew is formed on the dorsal part of the leaves. The lesions often heal into pieces and eventually cause the entire leaves to die. The disease first occurs on leaves closer to the ground, and young leaves occur less often. Symptoms of downy mildew in vegetables are mainly characterized by: 1 mainly damage the leaves, the lesions are faded green or yellowish at the beginning, and there is not a clear perimeter; 2 grow on the surface of the disease (the leaves are mainly on the back) grow a lustrous Fungal layers (sporangia and spores); 3 The diseased parts mostly start from the leaf that is closer to the ground, and gradually expand upwards or inwards. The young leaves rarely occur. Pathogens: caused by fungal infections. The parasites of these pathogens are obligate parasites that can only absorb nutrients from living tissues and cells and destroy the host vegetable tissues and cells. Incidence and environmental conditions: The oospore remains in the soil in the diseased body, or it adheres to the surface of the seed for winter, and after the winter, it is transmitted to the leaf near the ground by means of the rain reverse splash effect, resulting in buds. The tube undergoes initial infestation. The climate is hot and cold, when it is sunny and rainy, the humidity in the field is high and the disease is heavy. Control methods: 1 Selection of disease-resistant varieties; 2 Seed treatment: 50) "Fushuangmei or 75% chlorothalonil seed dressing, the dosage is O.4% of the seed weight." 3 clean garden: a reasonable rotation, open the cabin around Ditch, reduce field humidity and groundwater level; 4 Pharmacy control: early onset or emergence of central diseased plants immediately sprayed, can be used 800 times solution of the epidermis; Rhizoctonia, Ruidu copper, 25% metalaxyl 1 (000 times liquid Spray, with special effects; also can be used on behalf of the Sen-Ammonium, Zeson Zun, Tuoting, carbendazim 80 () times liquid spray, spray attention when spraying on the back. (2) Vegetable Blight: can damage cucumber, wax gourd, pepper Vegetables, taro, potatoes, and other vegetables, the disease has risen in recent years, is an important disease, such as the environment is suitable, the disease occurs rapidly, often in the short term leading to the destruction of the whole field.Symptoms: due to differences in the performance of different varieties of vegetables symptoms: 1 Cucumber diseases damage the stems and stems of the vines, and leaves and fruit can also be damaged.The base of the stems is initially immersed in green water, the diseased part is contracted, the upper leaves gradually wither, and the whole plant dies.The diseased plant leaves, the diseased leaves Still green, stem damaged, diseased Kink, the upper leaves are withered, the leaves are damaged, the beginning of a dark green water spots, expanded to a near-round large lesions, the edge is not obvious, wet weather, often causing the entire leaf rot. 2 white gourd blight: Damaged melons, leaves, and vines.Melon disease occurs in the lower part of the tan blister lesions, the latter part of the depression, dense white mold on the surface of the sponge, rotten odor.Leaf lesions are brown, the edge is not obvious, the upper White mold, wet and damp leaves rot; 3 pepper blight: Many adult stages occur, the lesions are dark brown needle-shaped dots at the beginning of the disease, rapidly expand afterwards, the disease department is dark, the main stem is damaged, and the lesions can spread to the branches. Plants rapidly wither and die. Pathogens: Fungal Diseases Incidence and environmental conditions: pathogens wintering in seeds and seed potatoes, most of the diseases are spores, mycelia with the diseased plants in the wintering of the soil, the winter after the pathogen is mainly with the help of rain The anti-splashing action spreads the wintering pathogen adhering to the soil particles to the parasitic host, invades the host in a suitable climatic condition, causes the first soaking and reproduction, and then spreads again through airflow, rain, etc. The factors affecting onset include humidity, cultivation and management level, and disease resistance of varieties, among which humidity is the main factor. Under humid environmental conditions, the epidemic is generally serious, and all the areas are low-lying, poorly drained, and soil is heavy, after rain. Sites with waterlogging or leaking water near the ditch are heavy, nitrogenous fertilizers are applied extensively, management is extensive, and the humidity in large fields is also heavy. Prevention and control methods: 1 High sorghum deep ditch to strengthen flood prevention; 2 Rational rotation, increasing organic fertilizer; The use of disease-resistant and disease-free seeds;4pharmaceutical control;Prompt spraying protection is an effective measure to prevent the spread of the epidemic disease.Because the epidemic has a short incubation period and rapid spread, it should be carried out before the onset of the disease, 0.3% Bordeaux Cucumber can be used, pepper 0.5%, 1% concentration of potato and potato spray, can be sprayed with metalaxyl 500 times} dexamethasone 600 times solution, thiophanate, and dexamethasone 1000 times solution spray. (3) vegetable wilt disease; can damage pepper, tomato , cucumber, melon, loofah, watermelon and other crops. Symptoms: Solanaceous fruits are mainly expressed on leaves that are closer to the ground. The leaves yellow and then brown and dry. However, the dead leaves are not even detached on the stem. Sometimes the yellow leaves appear only on the side of the stem or leaf. The leaves on the other side were normal in color, and the vascular bundles were brownish when the stem was cut longitudinally or cross-sectionally. Fusarium wilt of melons. In the early stage of disease, the leaves at the base of the stem suddenly appear wilting. It is easy to be confused by the lack of water supply caused by the leaves. This kind of leaf is more obvious around midday, but it gradually returns to normal in the evening and continues to occur. A few days later, the whole plant died and the leaves did not fall off. In wet conditions, the surface of the diseased area often produces white or pink moldy material. Incidence and environmental conditions: pathogens with the disease residue left in the soil in the winter, can be carried out in the soil rot life, the seed surface can also carry bacteria. The pathogenic bacteria invaded through the root wound, and the pathogenic bacteria in the seedling stage only showed symptoms until the adult flowering. The soil in the vegetable field was acidic, the soil was heavy, and the onset was low. Prevention and control methods; (1) selection of disease-resistant and disease-free seeds for seed treatment; (2) crop rotation; (3) chemical control, spraying with carbendazim or benzene to 800 times, 1000 times for mancozeb Liquid spray. (4) Vegetable anthracnose: It can harm melons, cruciferous vegetables, peppers, eggplants, beans, and other crops. Distribution and hazards: Anthracnose in melons is an important disease on melon crops in our province. Pepper, Chinese cabbage and other crops often occur. The distribution is widespread and there has been an upward trend in recent years. Symptoms: Melon anthrax can cause atrophy and discoloration of the stem base of seedlings if they occur at the seedling stage. Causes a brown semicircular lesion on the edge of the leaf. In the adult stage, the disease mainly affects the leaves, stems, vines and fruits. The symptoms of different melons are slightly different. Pathogen: fungal disease. Incidence and onset conditions: The pathogens overwinter as the diseased plants remain in the soil. The pathogens can live on rot in the stubble plants. They can survive in the soil for 1-2 years. The pathogens infiltrate into the body from the wounds in the roots and the bacteria multiply in the catheter. , The catheter is blocked, water cannot rise, stems and leaves are dying due to water loss, germs are spread by rainwater, agricultural implements, humans and animals, when the rain is heavy, the humidity in the field, the acidity of the soil is high, and the weather is fine after a long period of rain or heavy rain. The temperature rises sharply and the incidence of bacterial wilt is even more serious. Prevention methods; (1) Crop rotation: The three-year cropping system in the general site of disease is best done in paddy-upland rotations; (2) Regulating soil acidity and alkalinity and applying lime and plant ash; (3) Improvement of cultivation techniques using narrow-narrow ravine cultivation. Cultivate strong seedlings and increase phosphorus and potassium fertilizers and trace fertilizers; (4) Chemical control: First discover diseased plants, remove and destroy, disinfect lime around, spray 100-150ppM of agricultural streptomycin or use enemy-dry double 500 at the beginning of disease. : 1000 times liquid filling pocket. (b) Occurrence and control of major pests in vegetables: 1. Small ground tiger (Bombyx mori, ground silkworm): Small ground tiger is one of the important pests of vegetable seedlings. It damages many kinds of crops. It is generally seriously affected by the first generation larvae. It was observed in May and June was the peak period of damage. 9 - Occurs in October. The 1st and 2nd instar larvae damage the heart leaves or young leaves of crops. The 3rd instar larvae cut off the young stems of the crops, resulting in the lack of seedlings and ridges. Morphological characteristics: adults dark brown, female moth antennae filamentous, male moth antennae base one-half double-node, the other filamentous, forewing grayish brown, near the edge of the wing with kidney-like pattern, ring pattern one, There are black edges around the lines. The hind wings are gray and white and veins dark brown. Eggs: Hemispherical, with vertical and horizontal down velvet on the surface, larvae: brownish to dark brown, with obvious topline, extremely rough body surface, dense black particles. The abdomen is hard brown and has two distinct dark brown bands.蛹: auburn, shiny, 4-5 section abdominal section on the back of the front edge of the center has a large engraved points; 5-7 section of the abdomen front also has a small engraved point. The abdomen ends with a pair of short stabs. Habits: 4 to 5 generations a year, with mature larvae or cockroaches wintering in the soil, with a generation of cockroaches. Before the 3rd instar, they ate in the daytime. After the 3rd instar, they crouched at night and took the food. The spray control must be in the 1st and 2nd instars. Occurrence conditions: The number of small ground tigers is closely related to the rainfall. Rainfall was more in the autumn of the previous year, and there was a possibility that the amount of rainfall was small during the March-April year. The rivers and lakes in general, low-lying land, poorly drained wetlands, and clays containing much water, have a lot of sand-flooding and are seriously endangered. Control methods: (1) trapping and killing adults, reduce the source of insects available 3 parts of 3 parts of vinegar, brown sugar, 1 part of white wine, 10 parts of water, add 50% of dichlorvos or trichlorfon by the ratio of 0.1% in total. In the evening, it was put into the field and trapped and killed to promote the trapping and killing of adults with tiger sex attractants. The effect was very good and could be adopted in large quantities. (2) Fine soil preparation, removal of weeds, elimination of sites for laying ground tigers, and cutting off the source of early larval food sources play an important role in reducing the damage of ground tigers. Chemical control: In the prevention and treatment of 3rd instar larvae, seedlings with holes, nicks and other injurious conditions, 800 seedlings of dichlorfon and dichlorvos are sprayed on seedlings and surrounding weeds to prevent and control. After the 3rd instar larvae were controlled, the bait was mixed with fresh grass, leaves or fried cilantro cakes, and cotton cakes. The bait was thrown into the field in the evening to seduce and kill. Artificially capture the larvae by opening the soil around the broken seedlings in the vegetable field or the victim strains left in the hole in the early morning. 2. Locust: Locust is a worldwide pest, which has a wide variety of crops. Apart from damaging melons, it can also feed on leguminous plants, solanaceous plants, cruciferous plants, and Malvaceae families. Adult and nymphs are on the back and tender. The shoots are sucked on the shoots and the leaves are killed, causing leaf curling and delaying the growth period. In severe cases, the seedling plants die of wilting and death. At the same time, they are the main spreaders of the virus disease and can also aggravate the occurrence and prevalence of stem blight. Occurrence characteristics: Aphids have high fertility and occur in multiple generations in one year, especially in dry season. Prevention and control methods: (1) eliminate host insects on overwintering winter, when the overwintering host and wing have reached 30%, spray phoxim or dimethoate 1000 times to prevent and cure; (2) remove weeds, winter and spring combined with compost to eradicate fields inside and outside , drains, roadside weeds, eliminating insect sources. Chemical control: When the aphid occurs in the spotting stage, dimethoate, no pine, l000 times liquid spray can also be used, can also be killed, killing 3000-4000 times spray. 3. The tobacco stem borer (Spodoptera exigua) is mainly harmful to crops such as pepper and beans in the vegetable crops. The damage to the pepper is the most serious. The larvae break into the fruit and affect the yield and quality of the pepper. The spread of soft rot occurred and caused serious losses. Occurrence characteristics: In the Changsha area, there were 4 generations in the year, and a few in 5 generations. The earthworms in the pepper plots were used for wintering in the earth room. The overwintering period was in the mid-to-mid-May period in May, each generation. The eggs hatch in early June. The larvae are at risk in the mid-July period and the moths are in full bloom in mid-July. The second generation of egg hatching period in the middle and late July, larvae endangered in the late July, the peak of the moth in mid-August. The third generation egg is in the middle and late August, and the larvae endanger the middle and late August. The fourth-generation egg hatching period in mid-September, from late September to early October most of the fourth generation of mature larvae into the soil overwintering. During the occurrence of H. assulta, the phenomenon of overlapping generations is very obvious. In July and August of the year, the number of occurrences was large and the damage was serious. Habits: Adults inhabit the peppers and leaves during the daytime and make activities. They have a tendency toward black light and willow branches. Adults like to lay eggs on peppers and tobacco. After the larvae hatch, they eat the eggshell and then feed. After 3rd instar, the buds begin fruiting and have the habit of turning fruit. Rainwater is an important factor affecting the occurrence of H. assulta. Rainwater is unfavorable for many years, and the drought year is beneficial. Control methods: (1) winter plowing and ploughing; (2) timely removing insects, eliminating fruit larvae, and preventing fruit transfer damage; (3) cutting tobacco to trap adult overwintering eggs, concentrated sterilization; (4) ) Black lights and willow branches trap and kill adult insects. Chemical control: Trichlorfon 800 times. For enemy killing and rapid extinguishing and killing of 3000 times liquid spray, it is necessary to grasp that the larvae do not invade into the fruit prior to harm. At the same time, the enemy killing and rapid extinguishment killing should be used alternately with other pesticides, otherwise it will cause the occurrence of large tea seedlings. 4. Tea Yellow (White Spider): Tea Yellow, which can harm a variety of vegetable crops. In recent years, the damage to the pepper is very serious. It has a great impact on the yield and quality of the pepper, resulting in losses of up to 40%. Occurrence characteristics: in the south can naturally winter, strong reproductive power, the body is very small, the general eye is not careful observation, it is difficult to find. The tea plants have a tendency to tenderness, so they inhabit more young parts and feed on them. They especially like to feed on the back of young leaves. They suffer from pepper damage. The back of the tea leaves are stained with oil, and the gradient is brown. The leaves are curled downwards and the young stems are changed. Yellow-brown, severely damaged plants are short and bunched, falling and fruiting, forming a bald tip, and the fruits of the pedicel also turn yellow-brown and lose luster, and the fruits grow stagnant and harden. The upper leaves of the eggplant became stiff after being damaged. The back of the eggplant was gray-brown or brownish-brown, oil-like, and the leaf margin curled downwards. The stems, stalks, stems, and fruits became gray-brown. The eggplant strains were seriously injured after the camping period. Can't bloom. Most of the umbilical parts of young fruit after flowering appear pale yellow, and as the fruit grows, it gradually turns dark brown, and the peel cracks and the seeds are bare. Control methods: (1) Eradicate the weeds in the fields, clean the pastoral areas, and promptly destroy litter and eliminate insect sources after harvesting. (2) Chemical control, starting in late May, the first priority is to check the edge of the house on the side of the dam. The central site of the hill is found to be harmful to the plant. It should be sprayed in a timely manner, focusing on treatment, from the end of June to August every 10th. 15 days spraying time, 3-4 times in a row, spraying the emphasis on the upper part of the plant, especially the back of the young leaves and tender stems, flower and young fruit can choose dicofol 10 ∞ times liquid; killing special 800 times spray; Good results. 5, melon wild medlar: The main damage cucumber, wax gourd, gourd, bitter gourd and other melon crops, particularly serious damage to the melon, larvae harm the leaves, tip shoots, picking damage melon strips, with serious damage to the leaves. Occurrence characteristics: Melon pods occur 6 generations a year. The mature larvae and crickets live overwintering in the dead leaves of the dead leaves. Generally, they begin to see in May and begin to damage by the end of May. The occurrence of large amounts in the three months from July to September is the end of October. The larvae can still be seen on gourds, cucumbers, and loofahs. The eggs are produced on the back of the leaves and are produced in small quantities or in small numbers. After 3rd instar larvae are spun, the leaves are conjugated, and they are hidden in danger. In severe cases, The leaves were exposed to light, leaving only the veins. The larvae not only eat the young fruits and flowers of melons, but also break into the melons. The larvae are lively. When they are scared, they droop and droop, and they are harmed. After the larvae are mature, they can whiten the pupa at the victim's site or disperse them in the top soil of the rhizosphere. Control methods: (1) For the prevention and control of melon wild leeches, larvae should be mastered during the peak incubation period, and dimethoate or trichlorfon can be used to spray 1,000 times, and the enemy can kill or quickly extinguish and kill 4,000 times liquid spray; ( 2) Manually remove the affected leaf roll and eliminate the leaf larvae; (3) After the melon crop is harvested, the wilt and fallen leaves should be promptly collected and burned to eliminate the insect source.