Gill grasshopper is a general term for various physiological diseases and invasive diseases in rice seedlings. Physiological gills are common: rotten species, rafting, "black root" and so on. Rotten seed is not germinated and rots after sowing, or young buds are rotted and rotted in the muddy layer of the rock board. Rinsing is a long time after budding can not take root, rice buds floating dumping, and finally rot to die. The above two are due to the poor quality of seed, the heat or chilling of rice seeds in the process of germination, or the poor quality of soil preparation in Putian, the deep water storage, and the lack of oxygen and suffocation, which are strictly speaking not within the scope of disease. "Heigen" is a phenomenon of poisoning. When unfermented green manure or large amounts of organic manure and ammonium sulphate seedlings are applied, water storage is too deep and the soil is reduced too strongly. Sulfate-reducing bacteria, which are widely present in the soil, rapidly reproduce, producing large amounts of hydrogen sulfide, iron sulfide, etc. Reducing substances, poisoning rice seedlings, make the rice root black rot, and the leaves gradually die. The surrounding soil is also black and there is a strong odor. Infestation rot mainly includes cotton rot and blight. First, the symptoms. Cotton rot: can occur within 5 to 6 days after sowing. In the initial stage, a small amount of milky white jelly appeared firstly from the gap of the seed coat or the base of the young bud, and white flocculent mycelium grows gradually to four weeks. It is radial, and is often rust-like and greenish brown due to precipitation of iron oxides or adhesion of algae and mud. Or earth color. The rot inside the invaded rice cannot germinate, or the rot of the diseased seedlings will die. At the time of initial onset, sporadic patches appeared in the fields of Sakata. If persistent low-temperature rehydration occurs, the sporadic spread can quickly spread. Blight: early victimization, withered plants, weak stem base, easy to pull off, later the victim's leaf is wilted and curled, stem base is soft rot, the whole plant is yellow and brown withered, the disease minister has white, pink or black mold layer . Second, the pathogen. Bacillus spp.: mainly caused by the genus Bacillus, including: Bacillus subtilis, Bacillus subtilis, Mytilus edulis, etc., belonging to the flagellin subfamily fungi. Mycelial tubular, without diaphragm, well developed and branched. When zoospores escaped, they first gathered at the opening of the sporangia and showed a resting state. After a period of time, the formation of renal zoospores with two flagellas is dispersed. Sexual reproduction results from the combination of sperm in the male and eggs in the ovipositor to form oospore. The oospore is spherical, thick-filmed, strong in resilience, germinated after dormancy, and internally formed to form zoospore. In addition, Pythium, Meshrium, and Pythium-like fungi sometimes cause rice seedlings to rot. Blight: mainly caused by the following fungicides. Fusarium fungi, including: Fusarium graminearum, Fusarium equisetius, and Fusarium oxysporum, among others, belong to the genus Aspergillus. Conidiophore sickle-shaped, curved or slightly straight, colorless and transparent, with multiple divisions, small conidia ellipsoid or ovoid. Equisetum Fusarium has a small number of small conidia, F. oxysporum is easy to produce small conidia and large conidia, and large conidial spores; hyphae can produce blue-green or dark blue sclerotia in the late growth stage. Rhizoctonia solani, which produces only mycelium and sclerotia. The young mycelium is colorless, branches into sharp corners, and is divided at the branches. The old cooked mycelium was light brown, separated and constricted, and the middle of the cell expanded and showed a ganglion-like shape. Sclerotia irregular shape, diameter 1 ~ 3mm, brown. Third, the incidence of law. The pathogens that cause gill rot are all soil habitual fungi that can sustain long-term rot in the soil. M. mildew and Pythium bacteria are also commonly found in sewage. They are generally not susceptible to infestation of robust seedlings. They are only harmful when the seedlings become debilitating. Pythium is overwintering in the soil with hyphae and oospores, and zoospore is transmitted by flowing water. Fusarium is commonly spread on mycelium and soil in various host remnants and mycelium spread by mycelium and mycelia. The germigenic conditions of infestation rot are more or less often present, and the dominant factor in the occurrence of rot is seedling disease resistance. When the weather is bad and the management is not proper, the seedlings are debilitated and various kinds of weak parasites take advantage of it. Low temperature and rain, lack of light is an important factor that causes rotting, and the low temperature affects the most. The cold resistance of seedlings is related to the type of seed, seed quality, seedling growth period and growth status. Due to different environmental conditions, there are differences in the causes of rotting in various types of paddy fields. In infestation rot, mulch rot is relatively heavy in wetlands, light in moist irrigated fields, and rarely occurs in flooded fields. Putian is located at the outlet and is vulnerable to cold winds. The temperature of the water drops and the rotting is serious. Insufficient light, Putian, rotten embarrassment is also more serious. In addition, the soil is soft and soiled, and the soil is extensively planted. After sowing, it is often due to seedlings falling into the mud and causing rot. The seesaw is not flat, and the accumulation of water impedes the respiration of the shoots, or the seedlings at the uplift are susceptible to frost and sunlight burns, all of which can cause rot. The content of carbohydrates in seedlings is the material basis of cold resistance. Where the application of available nitrogenous fertilizer in Putian is too dark and green, and the ratio of carbon to nitrogen is low, the cold resistance is poor. In case of low temperature, it is easy to induce rot. The irrigation technology of Putian is also closely related to the rot. With proper control of water volume, it is possible to reduce or avoid the occurrence of rot even under adverse external conditions. When the temperature of the cold winter comes down, if it fails to heat the water in a timely manner, or if it is poured into the rain for a long time, or if it is irrigated with sewage, it is easy to rot. Fourth, disease control. The prevention and control of rotten roaches should be based on the improvement of breeding techniques, improvement of environmental conditions, and strengthening the resistance of rice seedlings to disease resistance. 1. To improve the way of raising children and ensure that the quality of Putian should be adapted to the local conditions by using plastic film breeding and greenhouse steaming. The open field nursery should be improved on the basis of wet field. Putian should choose to shelter from the wind, the terrain is relatively high and flat, and the fertility medium irrigation is convenient. Land preparation strives for fineness. Every winter field Tianzuo paddy field to winter plowing, full base fertilizer, apply more temperature fertilizer, in order to increase the soil temperature and permeability, remove the weeds and rice roots before sowing. 2. Select all kinds of valleys to be pure, clean, and healthy. Before the soaking, do a good job of drying seeds to increase the seed's viability and germination rate. After drying, wind dressing, salt (mud) water seeding and germination after soaking seed germination. 3. Improve soaking and germination techniques Soaking and germination should be controlled in the temperature is basically stable above 10 °C, germination, grasp the temperature and moisture. 4. Grasp the short-term planting, pay attention to the quality of sowing in early spring and frequent cold weather, the weather is changeable, the southern rice area must be in the local daily average temperature above 12 °C in order to plant a large number of exposed ridges; northern rice area generally use waterbed or improved waterbed breeding, The temperature should be sown at 10°C. The amount of sowing should be appropriate, the falling valley should be uniform, and the valley (collapsed) cannot be seen. Covers should be made of warm, fertilizer-efficient grass ash, etc., according to local conditions. After sowing, they should be allowed to naturally dry and dry. Warming ventilation eliminates reducing toxicants in the soil, which helps to take root and produce seedlings so that the seedlings can be homogeneous, full, even and strong. 5. Scientific management of water, reasonable fertilization in the water to do both to control the water courage to promote root, but also warm irrigation nurse seedlings. Generally keep the water incubating. Fertilization should grasp the principle of stability, lightness and heavyness, so that the seedlings “get nitrogen and sugar†and enhance the cold resistance. 6. Chemical control During the three-leaf stage of rice, 65% to 70% of enkeson 1000 times or 5.5% of Soaking Spirit II 3000 to 5000 times of 2 to 3 kg per m2 will be poured to control the effects of seedlings withered and withered. Significant; 5.5% Soaking Spirit No. II No. II EC 5000 times soaking seed, a significant control effect on the damping-off period of the needle; soil acidification treatment and hymexazol treatment of the seedbed soil can also effectively control the rice field Blight, Blight disease.
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