Early defoliation is a common leaf disease in apple growing season. It mainly includes brown spot, grey spot and round spot disease. The most common and most harmful ones are apple spotted leaf disease and apple brown spot. The overwintering site of apple spotted leaf disease is in victim leaves, shoots or bud scales. Spores are produced in the spring, and with the spread of wind and rain, there are two peak periods in one year. The first time in the period from early May to mid-June, the second time in September. The main damage to young leaves, especially the young leaves within 20 days of exhibition, is the most vulnerable. In the early stage of disease, brown spots appeared on the leaves, and there were purple halos around. When the conditions were appropriate, several lesions were connected, and finally the leaves scorch off. Apple brown spot mainly winters in fallen leaves. Spores produced in the spring are splashed with rain on leaves that are closer to the ground, becoming the primary source of infestation, re-infecting with wind and rain after a period of incubation, onset in May-June, and the onset of disease in July-August. . The main infestation of the old leaves, the lesions on the leaves were brown dots at the beginning, after which they could develop into three types of lesions of the ring pattern, needle-type (the most common), mixed type, causing the old leaves to yellow and fall off, but the lesions The edge remains green to form a halo. 1 Incidence of the law The pathogenic bacteria overwintered on the deciduous trees with mycelium or conidium discs, and conidia occurred after rainfall in the spring of the second year, splashed onto the leaves under the canopy with rainwater, and became the source of the initial infestation bacteria, followed by multiple infestations. June-July is the peak period. The leaf spot was a fly-catcher-like brown spot at the beginning, and there was no clear boundary with the healthy part. Later, it developed into a concentric ring-shaped pattern, a needle-shaped pattern, and mixed-type spots, and it turned yellow off. 2 Incidence conditions (1) Rainwater. Rainwater is a major contributor to the spread of germs and diseases. It can produce large numbers of conidia in April-May when it is rainy, and it needs enough rainwater to spread and invade. The conidial period of incubation is generally 6-12 days and the longest is 45 days. It takes about 13-55 days for the onset to fall leaves. Therefore, in the spring and rainy seasons, the summer rainy season ahead, high temperature and high humidity, the disease will become a pandemic. From August to September, the leaves of the susceptibility cultivars will mostly fall off. The severe lessons of defoliation in many fruit areas in Hengshui last year confirmed this. (2) Tree vigor. Where the terrain is low, the canopy is closed, and the conditions of ventilation and light transmission are poor, the management is extensive, the imaginary trees, the weak trees, the branches are thin and soft, and the leaves are small and thin, and are extremely susceptible to disease. (3) Variety. Marshals, Fuji, Jinshou, and other varieties suffer from severe disease, and Qinguan and Jura strains have a low incidence. (4) Closed. Due to improper trimming, the orchard is closed, and the conditions for ventilation and light transmission are poor, creating extremely favorable conditions for the occurrence and epidemic of germs. These types of orchards are more severely affected by mid-lower parts and internal hemorrhoids. (5) Exfoliation (cutting) is too heavy. The early defoliation disease showed the most obvious effect on apple bitter pitting in the girdling (cutting) tree, especially the trees that had been hacked for years. (6) Paralysis. Many farmers are "not seeing rabbits not hawking" in the prevention and control of pests and diseases. They often miss the best period of prevention and treatment. It is too late to wait until the onset of disease. Because of the latent period of early defoliating bacteria, especially the brown spot, it takes 6 to 12 days to lurk, and it takes 13 to 55 days from the symptom to the diseased leaf to fall off. (7) Improper medication. Symptoms have already emerged. Some farmers have not been able to apply drugs or buy low-level medicines, resulting in more serious fights. 3 Prevention measures (1) Strong tree power. Strengthening the management of orchard and soil water in orchards and enhancing tree vigor to improve disease resistance is the fundamental measure for preventing and controlling diseases. (2) Transform the closed garden. When the closed orchard is cut in winter, it must be reformed vigorously. Regardless of the shape of the tree, the requirements for “open flow, no connection, ventilation, transparency, and ease of operation†must be met after the transformation. (3) Do a good job of artificial cleaning. Combining the winter shearing and cutting off the branches and branches of the trees, the apple planting low-carbon node-sourced planting technology is cleared together with the ground deciduous trees, and is destroyed centrally to eliminate the pathogenic bacteria that overwintered on it. (4) Chemical control. Prevention and treatment of spotted defoliation disease should focus on two prevention and control peaks: the spring shoot stage begins spraying after falling, once a day for 10 days, and even spray 3 times; autumn shoot stage sprays 1-2 times depending on the condition. Prevention and treatment of diseased spotted deciduous disease began from late May to early June, and sprayed once every 10-15 days, and sprayed 4-5 times according to the amount of rain. The preferred pharmaceuticals are M-45, 1.5% polyoxin and others. 4 spraying requirements (1) Pay attention to spraying before rain. To timely and accurately listen to the weather forecast, it should be sprayed on the afternoon of 1-2 days before the rain. (2) Pay attention to the selection of good medicines to ensure the control effect. (3) Select high-pressure maneuvering sprayer, it is better to use sprayer with good atomization effect and avoid using spray gun. (4) Be careful and considerate, especially the inside and outside of the canopy, the up and down, and the front and back of the blade. Disposable Protective Coverall Suit,Disposable Ppe Protective Coverall Suit,Disposable Protective Coverall,Medical Simple Protection Suit GULF STAR MEDICAL MANUFACTURING FZE , https://www.gulfstarmedical.com