How to control apple tree rot when trees are weak, branches, dead and dead?

Apple tree rot, commonly known as rotten skin disease and smelly skin disease, is one of the main diseases of apple trees. The disease harms fruiting trees, resulting in tree weakness, withered branches, serious death of trees and destruction of gardens.

Apple tree rot

Symptoms: the main disease of apple tree rot harms the trunk and branches, as well as branchlets, young twigs and fruits. According to the symptoms of branches, it can be divided into ulcer type and branch withered type. Ulcerative type: occurs on the trunk and main branch, the bark of the diseased part shows reddish-brown water-stained micro-bulge to oblong spot, the diseased part is soft, easy to be torn, hand pressure is sunken, yellow-brown juice flows out, strong wine lees smell, gradually dehydration and shrinkage, cracks are produced at the edge, and small black spots grow. Small black spots can gush with yellowish-brown tendrils when it is wet. Branch withering type: occurs on 2-5-year-old branches, the edge of the spot is not clear, not raised, not waterlogged, infected branches dry up, the spot gradually grow small black spots, serious harm to apples, light brown rot, with the smell of wine dross.

Incidence regularity: there are two high incidence periods of apple rot in a year, March-April and July-September. When the temperature rises in early spring, the sap begins to flow, the nutrition turns to the growing point, the branch of the tree has less nutrition, coupled with the sunny warming of the tree, the nutrition is unbalanced, and the disease resistance of apple trees decreases, which leads to the spread of disease spots and the formation of the peak of disease in spring. Then, the disease spot expands rapidly and does serious harm, often causing dead branches and trees. From May to June, the tree has luxuriant branches and leaves, nutrients begin to accumulate to the branches, the disease resistance of the tree is enhanced, and the disease spot stops expanding. From July to September, the apple expanded rapidly, needed a lot of nutrients, the tree nutrition decreased, the disease spot began to expand, and the autumn peak appeared. It can be seen that the strength of the tree can affect the severity of rot. Tree nutrition imbalance, too much fruit, too many wounds, serious freezing injury, lack of fertilizer, drought, early defoliation, large occurrence of spider mites, and serious rot.

Prevention and control measures:

Strengthen cultivation management: increase organic fertilizer, phosphate fertilizer, potassium fertilizer, balanced fertilization; thinning flowers and fruits, control the amount of hanging fruit, prevent the year of apple; spring irrigation and autumn control, reasonable irrigation; reduce and protect wounds, smear the saw with 843 rehabilitation agent; strengthen the control of diseases and insect pests to avoid early defoliation of apple trees After defoliation in early winter, dry it with whitening agent made of quicklime, 20 Bomedo stone-sulfur mixture, salt, animal oil and water according to the ratio of 6 ∶ 1 ∶ 1 ∶ 0.1 ∶ 10; cut off diseased branches in time, scrape off diseased spots and warped skin, take them out of the garden and destroy them centrally. Fungicides to kill bacteria: spray 3-5 Baumedushi sulfur mixture on the whole tree once before sprouting in early spring. Timely treatment of plaque: first, pack mud. Add the right amount of water and clay, smear 3-5 cm thick on the disease spot, the mud layer should be 4-5 cm beyond the outer edge of the disease spot, then wrap it with plastic sheet and tie it tightly. The second is cutoff. Use the knife to draw a circle along the outer edge of the lesion 1cm, the knife edge is deep to the xylem, and cut several knife edges up to the xylem longitudinally and horizontally, and then smear 843 rehabilitation agent or 21% peracetic acid water agent 2-5 times, the edge should be beyond the outer edge of the lesion 3cm. One month later, apply it again. The third is curettage. Use a sharp knife to scrape off the spot, down to the xylem, and scrape off the healthy bark of 0.5-1cm at the edge of the spot, and then smear it with a 50-fold solution of 5% bacteriological detergent or 843 rehabilitation agent. The disease is easy to relapse and should be examined in time in summer and autumn. The fourth is bridging. The major disease scars on the trunk of apple trees can be bridged in time. Generally, one-year-old robust branches are selected as scions in spring and bridged at the upper and lower edges of the disease spot. When the disease spot is large, multi-branch bridging can be carried out. In addition, it can also be connected with the foot of the tillering bud.