(I) Symptoms: The root rot of apples is mainly responsible for the roots of the plants, and they first develop from the roots, form red-brown round spots around the fibrous roots, and then spread to the large roots connected to the fibrous roots. The lesions expand and connect to each other and go deep into the xylem. Make the whole root black and die. There are four types of symptoms in the upper part of the fruit tree after the leaves are displayed in April-May: 1 wilting type: The whole or part of the branches of the diseased plant grows weak after sprouting, the leaf clusters are wilting, the leaves are curled upwards, the shape is small and the color is light, the new shoots are difficult to pick, and some even the buds cannot shrink, or After flowering, the fruit can't result in water loss, and even the cortex can shrink or die. 2 Leafy dry type: In early spring or when the temperature is high, the diseased leaf suddenly loses water and dryness. Most of the diseased leaves develop inward from the leaf margin, or extend inward along the main vein. There is a clear boundary between the dry and healthy tissues. Red-brown halo with severely dry leaves falling off. 3 Leaf margin coking type: The tip or edge of the diseased plant leaves are defocused, while the middle part remains normal, and the leaves do not fall off quickly. In many years of the rainy season, the disease develops slowly and is the main symptom of the disease. Four branches of the blight type: a few of the main branches corresponding to the rot roots of the diseased plants are necrotic, the diseased parts become depressed, and spread along the branches. In the late stage of disease, the necrotic cortex is easily peeled off, which is a special symptom presented by partial large root rot. (2) Pathogenesis: The pathogen of apple root rot is mainly caused by Fusarium oxysporum and a small amount of Fusarium solani, all of which belong to the semi-known fungi. It can survive long-term rot in the soil, but also parasitic, only when the roots of fruit trees grow weak, the bacteria invade the roots and cause plants to attack. In follow-up investigations of various types of orchards, it is found that: 1 When fruit trees are girdled or circumcised for a long time, often Severe onset. 2 Orchard management is extensive, organic fertilizer is less used, and debilitated persons suffer from severe disease. 3 Severe compaction of soil, low topography, and heavy water incidence. (III) Prevention and control measures: 1 Strengthen management, increase tree vigor, and increase plant disease resistance. Applying organic manure in orchards, fertilizing soil fertility, improving soil permeability, increasing potassium fertilizer, and promoting root growth have a good preventive effect on the occurrence of root rot. Formula fertilization, N, P, K fertilizer reasonable coordination, to avoid partial application of N fertilizer. Rational pruning, controlling the amount of results, strengthening management measures, increasing tree vigor, and reducing disease incidence. Once the diseased orchard is found in the orchard, dig deep trenches more than one meter deep around the diseased plant and block it to prevent the spread of germs to neighboring strains. 2 disease tree cultivation and management measures. Take timely remedial measures on the diseased plants to reduce the incidence and reduce losses. First cut off the dried fruit branches and reduce water transpiration. The second is to reduce the amount of fruit trees and promote root growth. Third, spring and autumn yam soil to root, can be aired to the roots, scrape the diseased part or remove the root, during the rooting to avoid water or rain within the tree point, dry 7-10 days, scrape the disease after the rooting with the agent, The disease-free soil was then selected for coverage. Fourth, the main stem is coated with 50-fold amino acid solution before germination in the spring, and amino acids (containing iron, calcium, and trace elements) 200 times solution plus 0.2% potassium dihydrogen phosphate and 0.2% urea are sprayed during the growing season. 4 times. 3 agent irrigate root. The number and time of pesticides irrigating the roots are best performed twice a year before and after the apple tree sprouts. When irrigating roots, roots are used as the center to excavate 3-5 radial grooves and grow to the circumference of the canopy. The grooves are 30-45 cm wide and 50-70 cm deep, depending on the depth of the root system. Dig out the root of the disease, pour 0.5% copper sulfate solution, and fill it with disease-free topsoil. Suture Needle,Chromic Catgut Suture,Chromic Suture,Medical Disposable Suture Surgimed Medical Supplies Co.,Ltd , https://www.surgimedcn.com