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Pathogen: A basidiomycete subphylum fungal strain. 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.
Occurrence pattern: The sclerotia is mainly wintered in the soil or attached to the diseased tissue and can survive for 5 to 6 years under dry conditions. 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.
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. Use 70% of pentachloronitrobenzene for 1 to 2.5 kilograms of each side of the drug, and mix the soil surface with fine soil. 7 to 10 days after the sprinkle. Seedlings with lesser susceptibility can be irrigated with liquid medicine. There are 50% carbendazim 500 times solution, 0.5% copper sulphate solution or 50% thiophanate-methyl 500 times solution. Transplanting tea leaves can be sterilized with 20% lime water.
Tea Root Cancer (compared with Blight)
Distribution and Symptoms: The main damage to tea seedlings occurred in some tea areas, causing tea seedlings to die. 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.
Pathogen: Tea root cancer is a 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.
The law of occurrence: The root cancer bacteria live in the soil or diseased tissues. 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.
Control methods: strict seedling inspection, prevention of underground pests, and reduction of root wounds. When necessary, seedlings can be soaked with 20% lime water for 10 minutes and then transplanted.
Root-knot nematode disease
Distribution and Symptoms: Mainly distributed in warm tea producing areas such as Hainan, Guangdong, Guangxi, Taiwan, Zhejiang, and Fujian. 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.
Occurrence pattern: Root-knot nematodes are aerobic organisms that are hi-dry and dry. They occur in multiple generations in one year. When the soil temperature reaches 25-30°C and the soil moisture is about 50%, they are found in sandy soils with high topography and loose soil structure. The first generation can be completed within 20 to 30 days, while the nematode occurs more in the top soil than in the bottom soil, and stops when it is below 10°C.
Control methods: 1 Select wasteland for nursery, if it is planted peanuts, melons, beans, sweet potatoes and other crops is not suitable for nurseries, if you need to be used as a nursery should be soil disinfection, with 3% per 667 square meters Carbofuran 5 kg of fine soil was sprinkled on a seedbed, or 2.5 kg of dibromopropane per 667 square meters, and the seedbed was watered 100 times, and then the basal fertiliser and the soil were placed. In the midsummer, the soil should be deeply turned and exposed to sunlight for 10 days and then turned over again to kill the nematodes in the soil. 2) Increase the resistance of diseased seedlings by applying phosphate fertilizer and potash fertilizer; at the same time, use a 100-fold dilution of 80% dibromochloropropane emulsion to inject 3 ml of holes into the diseased plants, then cover the holes with soil, or use lime. Nitrogen, enemies, methyl isothiophos and other drug control. With 1:20 tea dry water applied to the soil also has a good control effect.
Tea purple feather disease
Distribution and Symptoms: It is distributed in various tea production areas in the country, but it is 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.
Occurrence pattern: Generally, the incidence of heavy springs and summers at the turn of the spring and summer or summer and autumn is heavy, and tea gardens with high groundwater levels, poor drainage, and excessive soil drying are easy to develop. 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.
Control 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 1000 dilution. Half an hour later planting. Drainage and tea gardens with high water levels should pay attention to drainage. Drainage trenches should be dug before boring. Land that had previously been planted with sweet potatoes, potatoes, and fruit trees and had the disease had to be disinfected with 70% quintozene, soil disinfection with 2.5 kg fine soil per 667 square meters, or formalin 30 The water was used to irrigate the soil with multiple dilutions. The roots and necks were watered with potassium permanganate or a 1000-fold dilution of the water in the early stage of the disease.
Tea leaf root disease prevention and control methods
Distribution and Symptoms: Tea seedling disease is a common root disease in nurseries. The country has a wide distribution and 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.
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