Causes and prevention methods of apple root disease

Apple is a common fruit in life, tastes sweet and delicious, and is rich in nutrition. It is one of the most popular fruits. However, the occurrence of apple root disease will cause apples to gradually reduce production, and finally until the apple tree dies.

Apple root disease damage symptoms

The symptoms of root disease on the tree are: local or whole plant leaves become smaller, the leaves on the branches gradually turn yellow from the bottom to the top, and even fall off, the growth of new shoots becomes smaller, but the results are more, the fruit is less taste. The underground part begins to occur from the roots of small roots, large roots or roots and necks, and then spreads rapidly. If the roots and necks rot a circle, the whole tree dies. The surface of the diseased part is purple-brown, water-stained, sometimes oozing brown juice, and the diseased tissue has a strong mushroom smell. When the condition is serious, the xylem of the diseased part is also decaying. Fresh diseased tissue emits noticeable light green fluorescence at night, which is characteristic of the disease. In the hot and rainy season, the mushroom roots are often clustered in the roots and necks of the diseased trees.

The occurrence rule of apple root disease

Apple root pathogens mainly overwinter the mycelium on the roots and residues of the diseased plants. When the roots are in contact with the roots and their residues, they secrete the gelatinous adhesion, and then the branches directly invade the roots, or from the wounds. Intrusion. The spores of the root pathogen fall on the residue. Under suitable environmental conditions, the spores can germinate, produce hyphae, extend to the roots along the pile, and grow the root fungus. When the rhizopus enters the root, it directly or produces multiple branches to invade the root, leading to disease. The pathogen is very weak and can survive on the residual roots of the soil for many years. Therefore, when the old forest land or the old orchard site is built, the root disease is often more common. The occurrence of the disease is from March to April and from August to September.

Apple root disease condition

The occurrence of apple root disease is closely related to soil moisture, environment, texture and tree potential: 1 soil moisture. The growth temperature of the roots is 25-30 °C. Under the moderate temperature, if the soil moisture is too large, the bacteria will expand rapidly; the soil will be dry for a long time, the relative humidity is below 5%, and the bacteria will die easily. 2 soil environment and texture. In the woody and humus soil rich in roots and decay, it is conducive to the spread of the bacteria. Sandy land orchards are heavier than clay. 3 tree potential. The results of the tree are too many, the results of the year and year are serious, and the prevention of pests and diseases is not good, resulting in a large number of leaves, which can cause the root growth of apple trees to be poor, thus triggering the occurrence of root disease.

Apple root disease prevention and treatment method

1. Strengthen the management of orchard and improve the disease resistance of the tree

For the orchard with soil compaction, the soil should be deeply changed, the mature soil layer should be gradually deepened, organic fertilizer should be added, and soil properties should be improved. In orchards in arid areas, it should be noted that after thawing in the spring, the trees should be shaved in time, and the orchards with conditions should be timely flooded. It is necessary to actively grow green manure, or cover the tree plate with straw and firewood to reduce the evaporation of water under the tree and improve the soil. For orchards with high groundwater levels, water should be drained in time to prevent root soaking for a long time.

2, trench isolation

For the orchard that has already occurred, digging a ditch over 1 m deep around the diseased tree or orchard ward to block the isolation of the bacteria to prevent it from spreading to the roots of the surrounding healthy trees. After the rain in the growing season, timely inspections are carried out to remove the diseased fruiting bodies and burn them.

3, disease tree treatment

Disease tree treatment is generally carried out according to the following procedures:

The first is to find the root of the disease and the location of the disease. First open the soil layer of the diseased tree and dig it to the base of the main root. Pay attention to the root and neck. After finding the lesion, follow the lesion to trace the incidence of the main root, lateral root and root.

The second is to remove the root cause. The entire rotten root of the diseased tree should be sawed from its base, and the root and neck lesions should be carefully scraped and traced down until the roots are dug. For most root diseases, all roots must be removed. During operation, care should be taken to protect the roots. The wounds should be disinfected with a high concentration of fungicide and then coated with a protective agent such as Bordeaux mixture. Commonly used agents are: l%-2% copper sulfate solution, 5° Be stone sulfur mixture, 50% antibacterial WP 200 times liquid, 50% carbendazim wettable powder 300 times liquid and sodium pentachlorophenol 300 times Liquid, etc. Preparation of medicinal soil: The ratio of 70% chloral nitrobenzene wettable powder to soil is 1:50, mixed evenly and then sprinkled on the roots.

The third is to promote the recovery of the tree. Light disease trees, as long as the roots are removed, disinfection protection, replacement of the soil or disease-free soil; severe disease trees, first cut the ground part, reduce water transpiration, then bridge the new roots in the roots and necks, or around the root neck Plant strong seedlings and bridge them to the trunk. At the same time, the application of quick-acting fertilizers and proper watering will prompt the tree to recover as soon as possible.

The fourth is root irrigation. In the early spring, late summer and fruit tree dormancy period, 3-5 branches with a width of 40cm and a depth of 60cm are circulated around the base of the trunk. The groove grows to the periphery of the canopy projection, and the infusion solution is based on the contact of the diseased root, and then covers no Disease new soil or medicine. 70% methyl thiophanate WP 800 times solution, 50% dexamethasone 500 times solution, 0.2% copper sulphate solution, 10° Be stone sulphur mixture, pentachlorophenol sodium 500 times solution, etc. Received better control results.

The fifth is to clean up the sick tree. For dead or dead trees, the roots of the diseased plants should be removed as soon as possible and transported or burned in time. The diseased soil can be disinfected with 40% formaldehyde 100 times solution or pentachlorophenol sodium 150 times solution. After replacing the non-toxic new soil, replanting.

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