The optimum temperature for conidia and ascospores of rotten fungi to germinate is 25 ~ 30℃, and they can germinate for a long time at 5℃. Extensive cultivation management and freezing injury are the main reasons for the epidemic of rot disease. Orchards with weak trees, such as low soil organic matter, poor soil hardening or water and fertilizer conservation, poor root growth, insufficient compound fertilizer, excessive application of nitrogen fertilizer, serious fruit hanging and early defoliation, are all serious diseases, and vice versa. In the late low-lying period, orchards are prone to freezing injury and serious diseases because of long water accumulation, greed for green and delayed dormancy. The periodic freezing injury in the north, which caused a large area of bark frostbite, is an important reason for the widespread epidemic of rot disease.

How to control apple tree rot

Scientific fertilization irrigation: balanced fertilization, increased application of organic fertilizer, bacterial fertilizer, etc. , increase the nutrient accumulation of trees and improve the disease resistance. Before and after fruit picking, apply organic fertilizer once according to "per kilogram of fruit 1~2 kilograms of fertilizer", and apply biological bacterial fertilizer once in the germination stage, and apply it in the border or hole. Appropriate topdressing during fruit expansion.

Reasonable load: according to the conditions of tree age, tree potential and soil nutrition. , thinning flowers and fruits, adjusting tree load. Because the yield of trees is fixed, the middle-level orchards generally keep fruit according to the leaf-fruit ratio of 40∶ 1, and the fruit setting of diseased trees is appropriately reduced.

Proper shaping, pruning and wound protection: Proper shaping should be carried out to avoid damaging the tree. Take timely measures such as applying healing agent to protect the knife edge and try to reduce all kinds of wounds, such as frostbite, sunburn and insect pests. , to prevent the invasion of germs.

Clean up the source of infection and do a good job in orchard sanitation. Branches and treetops cut down in winter are stored centrally and covered with film to prevent the breeding and spread of germs. Cut off diseased dead branches and piles in time, scrape off rough old skin, and thoroughly clean up dead leaves. , and centralized incineration or burial. Disease resistance induction

Spraying amino oligosaccharides and other immune inducers once before flowering and fruit expansion to improve the disease resistance of trees. Chemical control

Brush branches with chemicals. The trunk of the fruit tree is painted white after the leaves have fallen. In the young fruit stage, some chemicals such as thiophanate-methyl, thiamethoxam or Pythium oligoandrosaceus were selected and applied to the trunk 1~2 times. Before using chemicals, the rough old bark was scraped off and taken out of the garden for centralized burning.

The tree was sprayed with medicine. During the period from defoliation to germination in early spring, broad-spectrum fungicides with therapeutic effects, such as tebuconazole and thiophanate-methyl, should be sprayed on the whole tree, and the trunk, branches and other key parts must be carefully sprayed to reduce the source base of rot germs. At the same time, do a good job in the prevention and control of diseases and insect pests such as brown spot, mottled defoliation, rust, tetranychus urticae, golden moth, etc. in the growing period, so as to prevent premature defoliation of fruit trees and weaken tree vigor.

Scraping and removing spots, bridging and rejuvenating. Discovered lesions, timely scraping. When scraping, carefully scrape off the discolored tissue of the diseased spot and the healthy skin tissue connected with it for about 5mm, reach the xylem, evenly cut green to form stubble and prism, and the edge of the diseased spot is neat and smooth without stubble, and then apply thiophanate-methyl and other drugs on the diseased spot. Serious lesions exceeding trunk 1/4 should be bridged and rejuvenated in time.