Main diseases and prevention of tea root
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1. The distribution and symptoms of white tinea philoxeroides 1,1: White leeches of tea are a common root disease in nurseries. Wide range of distribution, serious damage. In addition to tea, there are still more than 200 species of plants such as melons, Solanaceae, hemp, tobacco, and peanuts. Occurred in the root and neck, the disease was a brown spot at the beginning, the surface of white cotton wool-like material, expanded around the neck after a round, shape or white lenticular fibroids, can be extended to the soil surface. The rapeseed sclerotia formed in the diseased part later, from white to yellow-brown to dark brown. Due to the pathogenic effect of pathogens, the cortex of the diseased plants was rotted and the transportation of water and nutrients was hindered. The leaves wilted and fell off and the whole plant died. 1, 2 pathogen: is a basidiomycete subphylum fungal genus. The mycelia were initially colorless, followed by brownish, dense, sclerotia. Sclerotia round, smooth surface, hard, dark brown. Propagation bodies, namely basal and basidiospores, are produced under humid and hot conditions, but they are not common and have little effect on disease transmission. The law of occurrence of 1, 3: mainly sclerotium in the soil or attached to the disease on the organization of winter, dry conditions can survive 5 to 6 years. At the turn of spring and summer of the second year, hyphae will germinate when the temperature and humidity are suitable, spread along the soil gap or spread with rainwater, irrigation water, agricultural implements, etc., injuring the roots and necks of the seedlings. High-temperature and high-humidity are conducive to the onset of disease, with the highest incidence from June to August. The soil is heavy, the acid is too large, the terrain is low, the tea grows poorly, and before it is a parasitic disease, the disease is also heavy. 1,4 Control methods: Select nursery for raw or non-infested crops. Pay attention to the drainage of tea gardens, improve the soil, promote the construction of seedlings, and enhance the resistance to disease. Infected nursery should remove diseased seedlings and disinfect soil in time. The agent used 50% carbendazim 500 times, 0.5% copper sulfate or 70% thiophanate 500 times. Transplanting tea leaves can be sterilized with 20% lime water. 2, tea root cancer disease (compared with the blight of tea) 2,1 distribution and symptoms: The main damage to tea seedlings, serious in some tea areas, causing tea dead. Common in cutting nursery, the main lateral root can be victimized. The bacteria invaded from cuttings or root wounds of the cuttings, resulting in light brown spherical protrusions at the beginning, and then gradually expanded like a tumor, small like miliary, large like peas, multiple tumors often healed into irregular large tumors. Nodule brown, lignified and hard, rough surface. After saplings are damaged, the fibrous roots are reduced, and the above-ground parts grow poorly or die. 2, 2 pathogens: tea root cancer bacteria belonging to the genus [Agrobacterium tumefaciens (S.et T.) Conn. ]bacterial. The bacteria are short-barreled with 1 to 3 polar flagella. An off-white, round colony forms on plain medium. The optimal temperature for development is 25-29°C and the lethal temperature is 51°C (10 minutes). Developed best at pH 7.3. 2, 3 the law of occurrence: root cancer bacteria in the soil or diseased tissue winter. When the environment is suitable the following year, it will be harmed by water flow, underground insects and farm implements. The bacteria invade from the wounds or cuts of the seedlings, grow and develop in the tissues, and stimulate the cells to accelerate the division and produce cancerous tumors. 2, 4 Prevention methods: To strictly check the seedlings, control underground pests, and reduce root wounds. When necessary, seedlings can be soaked with 20% lime water for 10 minutes and then transplanted. 3, tea root knot nematode disease 3,1 distribution and symptoms: Mainly distributed in the warm tea production area. The disease is caused by a very small nematode. When the nematode invades tea roots, it causes the roots to form tumors, resembling soybeans, rapeseeds, etc., and are of different sizes. The roots of the affected species need not be rooted, deformed, and sometimes the root end is thicker than the front end. The above-ground part of the diseased plant had poor growth, the plants were short, the growth was weak, and the leaves were yellow. In dry season, the leaves were easily detached and died. 3,2 Occurrence pattern: Root-knot nematodes are aerobic organisms that are hi and high in temperature and dry. They occur in multiple generations in one year. When the soil temperature reaches 25 to 30°C, and the soil moisture is about 50%, the soil is high in the topography and the soil structure is loose. In soil, one generation can be completed within 20 to 30 days, while nematodes in the top soil occur more than in the bottom soil, and they cease to be active at temperatures below 10°C. 3, 3 control methods: 1 choose raw land as a nursery, if it is planted peanuts, melons, beans, sweet potatoes and other crops is not suitable for nursery, in the summer should be deep-turning the soil in the sun exposure 10 days and then turn 1 Second, it kills nematodes in the soil. 2 The existing diseased seedlings should be supplemented with phosphate fertilizer and potash fertilizer; the disease resistance should be improved, and disinfection with lime or applying 1:20 tea dry water to the soil also has better control effect. 4. Distribution and Symptoms of Tea Purple Plumage Diseases 4.1 Distribution: Symptoms are distributed in various tea production areas, but are more common in North China and East China. The disease mainly occurs in the seedling stage and adult plant stage. It damages the roots or roots and necks. It first rots brownish roots or dark browns, then spreads to the lateral roots and becomes purple-brown after decay. The lesions are covered with purple-brown filaments. On the surface of the disease, there is a hemispherical granular granular nucleus and small stem base plus centimeter, which is often surrounded by purplish red seedlings. The texture is soft, and it is easy to peel off. The root cortex is also easy to exfoliate. In severe cases, the ground part is wilting and the new shoots are reduced. The diseased plant died. 4, the law of occurrence: Generally in the high temperature and rainy spring or summer or the summer and the turn of the heavier incidence, where the high groundwater level, poor drainage, excessive drying of soil tea plant easy to disease. The bacteria can survive in the soil for many years and operate with farming; rain, underground pests and roots contact and spread and spread. Long-distance spread can also be carried out when transporting carriers of seedlings and soil. Continuous crops and former susceptible crops are also susceptible to disease. 4, 3 Prevention methods: Use sterile seedlings to find the diseased seedlings in time to excavate and burn them out, wash the tools after use, and then immerse the rest of the seedlings with 20% lime emulsion for 1 hour, or 50% of the carbendazim for l000 times. Dilutions were soaked for half an hour before planting. Drainage and tea gardens with high water levels should pay attention to drainage. Drainage trenches should be dug before boring. Soils that had previously been planted with sweet potato, potato, and fruit trees and had been affected with this disease were disinfected with 70% chloronitrobenzene, 2.5 kg of fine soil per acre for soil disinfection, or 30 times diluted with formalin. The soil was poured into the soil and the root and neck were poured with potassium permanganate or a 1000-fold dilution solution at the beginning of the disease.