Apple tree rot, commonly known as rotten skin disease, is a devastating disease. The incidence of rot disease in the northern apple production area is serious. The trees are very ill, and the branches are incomplete. They often result in dead trees and destruction of gardens. In recent years, there has been an increase in rot.
First, the symptoms
The rot disease mainly damages the branches, causing the cortex to rot and necrosis, often showing two types of ulcers and branches.
The ulcer type mainly occurred on the trunk and branch, and the main branches and branch branches of the resulting tree were the most. The lesions are round or oval in shape, reddish-brown, water-stained, and gradually become loose and soft. Tawny sap often flows out. Afterwards, the cortex is wet and has distiller's grains. Diseased skin easily peeled, internal organization red-brown. In the latter part of the disease, the dehydration depression was hardened, gray-brown to dark brown, and the diseased and healthy junctions cracked. Black spots on the skin are densely covered with black spots of orange and colloidal spores when wet. In severe cases, the lesions spread around the branches for a week and the branches on the affected parts died of dryness.
Branches and stems occur mostly in twigs of twigs, fruiting benches, and dry pegs, and they are most often cut. The lesions are irregularly shaped, red-brown, and quickly spread around for a week, causing the entire branch to die. The late disease department also showed black small particles. In the debilitating tree, the symptoms of branch blighting are particularly obvious and can cause the main branch or the whole plant to die.
Second, the pathogen and the law of occurrence
Phytophthora infestans mainly survive in mycoplasma, conidia, ascospora, and spore horns in diseased tissues or on diseased stems that have been cut off, and can survive for about four years. All tree weaknesses, such as poor site conditions, poor management, inadequate fertilization, drought and water shortage, serious spider mites, defoliation, and root rot disease, serious fruit set size, and other factors all induce morbidity. Winter tree frostbite, damage and cut saw cuts, insect stings, sunburn on the sunny side of the trunk will also induce rot.
Third, prevention and control measures
1. Strengthen the cultivation and management of Zhuangshu disease resistance, reasonable pruning, adjust the tree vigor; adjust the tree load to overcome the size of the phenomenon; increase organic fertilizer, a reasonable match with nitrogen, phosphorus, potassium fertilizer and trace elements; do a good job of fruit trees to prevent cold, Reduce the frozen wound, the results of the tree painted white, commonly used whitening agent, lime: salt: water: animal oil 10:1:30-35:0.2, generally after the leaves of fruit trees carried out, smear dry height of 2 meters.
2. Clean the orchard to reduce germs, find lesions scraped in time; pay attention to remove diseased branches, stubble, diseased fruit benches during pruning; remove diseased branches, diseased dead trees in time to remove burnt; cut saws and other wounds with pharmacy or paint Closed to reduce pathogenic infections.
3. Pharmaceutics prevention: spray germicide before germination in early spring, the agents are: Gerrun, Schnering agent 500 times fluid; 3-5 degrees lime sulfur agent; 5% bacteria poison agent 500 times fluid and so on. From June to July, the above-mentioned medicaments can be used to brush large branches of trees, and prevention and treatment have obvious effects for several consecutive years.
4. Sickness treatment. Lesion curettage method: 0.5 cm around the sickle was cut with a knife and a protective ring deep in the xylem. Then the diseased skin and skin in the circle were completely scraped off, and the diseased tissues on the plastic sheet were scraped off and burned. . The exposed xylem was deep-cut with a knife and applied 1-1.5 cm. It can be applied with 5 times liquid of gerun, 5 times liquid of 5% bacteriostatic water solution and the like. Apply it again 20 days after treatment.
Mud dressing method: make mud cakes with water and mud, spread it on the sickle and its periphery in a 5-8 cm range, and a thickness of 3-4 cm, then fasten it with plastic cloth or kraft paper. This method should be carried out in the spring, and the next year the spring to remove the dressing, remove the sick tissue after disinfection and protection.
Foot connection and bridging: Foot jointing and bridging can increase the tree's ability to transport nutrients and moisture, help restore the tree's vigor, and extend the results of years. This method is widely used in the old fruit area, and the new fruit area can be actively promoted.
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