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The occurrence and prevention of grape root cancer
Root cancer, also known as root cancer, is a very common root disease on fruit trees. It can harm peaches, plums, apricots, apples, pears, red fruits, and other fruit trees. Grape root cancer occurs in major grape growing areas. Root cancer usually occurs on the root and neck and on the old vine near the ground. Because of the damage to the roots, the growth of the plant's shoots is debilitating, affecting fruit yield and quality, and causing death of the whole plant. Symptoms: The main damage to the root neck, main roots and lateral roots, the main vine more than 2 years old is also often near the ground. Seedlings occur in places where scions and rootstocks heal. Tumors protrude from the lenticels of the root. It is sometimes possible to form tumours on stems that are more than 2 years old, which can be as high as 1 meter above the ground. This is often closely related to the frost damage or mechanical damage of the stems. For example, the grapes grown in our region will be covered in winter. Overwintering, so that bacteria can easily invade from the wound, resulting in the formation of tumors on the vine. Tumor size varies widely, diameter 0.5-1 cm, spherical, oval or irregular shape; young tumor is light brown, surface rotation, rough and uneven; if continue to develop, the tumor outer cell death, color deepens year by year, The internal organization is lignified and becomes a hard tumor. Diseased seedlings showed no obvious symptoms in the early stage. The disease continues to develop, with impeded root development, less fine roots, debilitating trees, short stature, short stems, yellow leaves, early defoliation, and severe plant death. Infection spread: cancerous bacteria in the tumor tissue of the winter, or when the tumor tissue decay, the bacteria mixed into the soil, soil cancer bacteria can survive for more than 1 year. Due to the broad host range of cancerous bacteria, soil carriers are the main source of disease. The pathogenic bacteria are mainly transmitted through rainwater and irrigation flowing water; in addition, underground pests such as earthworms and soil nematodes can also be transmitted; and seedlings carrying bacteria are the main means of long-distance transmission of diseases. Incidence conditions 1. Wounds: Pathogens invade the host through wounds. Injury, mechanical injury resulting from cultivation, cutting of cuttings, marring, and other damages can all be pathogenic pathways. 2. Soil conditions: The incidence and soil temperature and humidity have a great relationship, soil moisture, conducive to bacterial infection and disease; soil temperature 22 °C is most suitable for the formation of cancer, soil temperature more than 30 °C, almost no tumor formation . Soil acidity is also related to disease. Alkaline soil is conducive to disease. Acid soil disease is less, soil quality is heavy, low-lying landform, poor drainage of orchards are more serious. 3, management: extensive management of farming, soil pests and soil nematodes, and a variety of mechanical damage more orchards, the incidence of heavier; cuttings when the wound healing is not good, the seedlings bred more incidence. Control methods: 1. Strict quarantine and seedling disinfection: Grape root cancer spreads mainly through long-distance seedlings. Therefore, when constructing a garden, avoid the introduction of seedlings or cuttings from the ward; if the diseased plants are found, the diseased plants should be completely removed; the diseased seedlings and cuttings should be sterilized, and soaked in 1% copper sulphate for 5 minutes, or 2% lime solution immersed for 1-2 minutes, planted after disinfection. In addition, avoid the introduction of old seedlings over 2 years old, because the old seedlings are susceptible to infection by pathogens. 2. Strengthen management of orchards: For neutral or slightly alkaline soils with root cancers, organic fertilizer should be added to increase soil acidity and improve soil structure. Soil cultivation and field operations should be avoided as far as possible to avoid root damage or damage to stem vines. Base; pay attention to control of underground pests and soil nematodes, reduce insect damage; usually fruit trees pay attention to drainage after rain, reduce soil moisture. Strengthen fertilizer and water management to increase tree vigor and improve resistance to disease. 3. Scrape or remove the diseased plants: When there are individual diseased plants in the garden, the soil around the root should be removed and the tumor should be completely removed with a sharp knife until the disease-free xylem is exposed. The scraped and sick tissue should be burned and coated with a high concentration of lime sulfur or Bordeaux fluid to protect the wound from re-infection. For serious diseased strains that cannot be treated, the roots should be removed and thoroughly cleaned up, and the roots must be burnt. Before transplanting, the soil that may carry the bacteria should be excavated and replaced with disease-free, fertile new soil.