Why do apples rot? Causes and control methods
Apple is a fruit we commonly see, and China is the world's largest producer and consumer of apples, with a planting area accounting for more than 40% of the world total. The larger the planting area, the more problems arise, and apple fruit rot is one of the more common phenomena, affecting apple yield and quality. So what causes apple fruit rot? Let's take a look.
1. Diseases
The main cause of apple fruit rot is disease, and a variety of diseases can cause it, mainly ring rot, black rot, anthracnose, brown rot, and Phytophthora fruit rot. The symptoms of fruit rot caused by these diseases also differ; for example, with ring rot, ring-shaped lesions appear on the fruit surface, and as the disease progresses, the lesions expand and cause rotting, while fruit rot caused by black rot has black rotting areas.
Control methods: Strengthen orchard management. Many diseases are caused by pathogens that overwinter and continue to cause damage the following year, so the diseases occur year after year. After harvest, thoroughly clean the orchard, collect weeds, debris, fallen leaves and broken branches and burn or bury them deeply in a centralized manner, then remove diseased branches, broken branches and dried branches from the tree and take them out of the orchard to burn in a centralized manner, reducing the pathogen sources. When disease is found, remove the diseased fruit promptly to prevent it from spreading to other healthy fruit, and spray chemicals for control.
2. Too much and too heavy girdling
Many fruit growers mistakenly believe that apples cannot reach high yields without girdling, so they girdle the tree multiple times, not only girdling the main branches but also the secondary branches. Combined with factors such as not applying fertilizer in time and improper fertilization, the tree becomes weak, giving bacteria and microorganisms an opportunity to invade, causing the fruit to rot and drop. According to practical production experience, the fruit rot rate of weak trees can reach 50%, while the fruit rot rate of vigorous, healthy trees is only within 10%.
Control methods: Do not girdle excessively during management; girdle reasonably according to tree vigor and fruit load. After girdling, promptly apply more organic fertilizer and other nutrients to supplement the plant's nutrition, improve disease resistance, and not give diseases an opportunity to invade. Also cultivate strong trees to reduce the fruit cracking rate.
3. High planting density
Fruit rot is mainly caused by bacteria invading through lenticels, wounds and so on. Some fruit growers plant at high density to increase yield, resulting in poor air and light penetration between plants, with a large number of branches and closed canopy between rows and plants. This environment is extremely easy for bacteria and microorganisms to survive and reproduce. Moreover, spraying treatment in this environment is poor, and the fruit surface cannot be evenly covered with the chemical, leaving opportunities for bacterial and microbial infection, thus causing fruit rot.
Control methods: Plant reasonably, and when the plants become closed in, prune promptly, cutting away some weak branches, diseased branches and dense branches to increase air and light penetration between plants, and spray chemicals to inhibit the growth of bacteria and microorganisms.
4. Long periods of rainy weather
If long periods of rainy weather occur during the fruit expansion stage, the root system will absorb a large amount of water and transport it to the fruit, causing the fruit to expand rapidly and crack, and with the intrusion of rainwater and the invasion of bacteria, the cracked fruit will turn into rotting fruit. Moreover, after apples are bagged, this phenomenon cannot be avoided either.
Control methods: In rainy weather, take good drainage and waterlogging prevention measures to avoid the plant absorbing too much water, and when bagging, choose high-quality bags with good water repellency and good air and light permeability.
The above are the causes of apple fruit rot and control methods. We hope this helps you. To learn more about apple cultivation knowledge, please stay tuned to us.