What are the symptoms of fruit tree nodule disease? What preventive measures are there?

What are the symptoms of fruit tree nodule disease? What preventive measures are there? Root cancer of fruit trees is a common disease in fruit trees, especially in nurseries, followed by apple trees, pear trees, peach trees, plum trees, apricot trees, grapes, cherries, chestnut trees and fig trees, which leads to the weakness of trees. So what are the symptoms of fruit tree nodule disease? How to prevent it?

First, the symptoms of the disease mainly harm the roots and rhizomes, and sometimes it can also occur on the main stems and branches. The clinical symptoms after onset are characterized by: causing cancerous malignant tumors at the affected site, with different sizes, uncertain appearance, dark brown to dark brown, unsmooth surface and hard wood. At the beginning of the disease, with the growth of the tumor, the malignant tumor can reach the size of walnut kernel and fist, and even the aperture exceeds 10-30cm. There are many sick trees, the trees are weak and the growth and development are not good. In severe cases, the whole plant can wither, but most of the diseased plants are pruned by seedlings and fruit trees.

Second, the bacteria causing root cancer mainly overwinter in the epidermis of cancer and tumor institutions, but also in the soil, where the bacteria can survive 1 year. The underground pests (such as clams, crickets, etc.) are eliminated mainly by precipitation and farmland irrigation. ) also has certain adhesion and disease transmission effects, and many bacteria in seedlings are effective ways to spread diseases over a long distance.

Bacteria spread from various wounds, especially transplant wounds, insect wounds and mechanical equipment wounds. After the invasion of bacteria, the pathogenic factor Ti plasmid was sent to the host cell, which made the cell become a constantly differentiated transformant cell, thus leading to malignant tumor. Even if there are no germs in the middle and late institutions, malignant tumors can continue to expand.

Generally, the onset period of root cancer is long, with onset in June-10, peak in July-August and ending in late June-10. Poor wet and cold management of soil and weak growth and development of trees are conducive to the occurrence of bacterial infection, while drying is not conducive to bacterial invasion. Soils with weak alkalinity, high viscosity, poor drainage pipes, serious diseases, serious soil diseases, mild acid soil diseases and PH≤5 are not easy to get sick. Cutting or chopping wounds is large and slow to heal, which is beneficial to bacterial infection; Grafting method buries the wound by loosening the soil behind the mouth, which makes the bacteria contact the wound, with high incidence and low incidence of budding.

3. Control technology 1, the cultivation and utilization of disease-free seedlings do not need old nurseries and plantations, especially the land where root cancer has occurred as nurseries; When grafting seedlings, the bud grafting method is strongly advocated, and the methods of line cutting and splitting are minimized. When planting, the mating interface is higher than the road surface, and the mating interface contacts the soil. When pre-breeding seedlings in alkaline soil, use acid-base fertilizers and organic fertilizers as much as possible to reduce soil acidity, and pay attention to the prevention and control of underground pests to avoid harm.

2. Make a detailed inspection before the seedlings are transported or planted. It is best to use the examination in the nursery. Try not to use seedlings with root cancer. If the seedlings have been transferred, after careful counting, it is found that the diseased seedlings must be replaced and destroyed immediately, and the remaining disease-free seedlings should be disinfected. Generally, 1% silver nitrate solution, or 77% wettable powder of calcium hydroxide and copper 200-300 times, or 30 times of organic pesticide Ganeiling (K84) is used for 3-5 minutes, or 100 times of copper hydroxide solution 10-20 minutes, or ampicillin/kloc.

3. Resolutely avoid multiple cropping. When creating a new plantation, you should choose a plot with good soil permeability and no water. When planting, choose high-quality strong seedlings with meticulous root system, developed root system and excellent grafting method, and choose high ridge planting. The upgraded old plantation cannot be built immediately, but the leguminous crops can be planted for two years before the garden is built.

4. Treatment result of diseased trees: When the root of the disease is found, all diseased organs are removed, and then 1% silver nitrate solution, 77% calcium hydroxide copper wettable powder 200-300 times, or 72% streptomycin sulfate soluble granules 1000- 1500 times are used. Scraped diseased organs must be thoroughly cleaned and damaged immediately. Secondly, irrigate the soil around the diseased tumor with 500-600 times of calcium hydroxide copper solution or 0.3% silver nitrate solution, and disinfect the soil.

5. Strengthen the management methods of plantation, apply more organic fertilizer, phosphorus and potassium fertilizer, pay attention to drainage and waterlogging prevention in rainy season, ensure that the rain stops and the fields dry, and promote the growth and development of roots. Acid soil should be improved by applying acid-base fertilizers, which is not conducive to the growth, development and reproduction of bacteria. When weeding and fertilizing, root wounds should be avoided as much as possible. In winter, the dead branches, leaves and weeds in the garden should be removed, and the bark of the tree stems should be removed to prevent the occurrence of root cancer.

6. Pay attention to direct control of underground pests, such as grubs. When working in the field, try to avoid wounds, and pay attention to disinfection and maintenance of various wounds to reduce the spread of bacteria.

7. Biological control of root cancer in apple, pear, peach, cherry and other plants. Before planting, soaking roots or cuttings with the bacterial suspension of Agrobacterium radiobacter (bacterial concentration is 0/06 bacteria per ml/kloc) can effectively prevent the occurrence of root cancer.