Apple early defoliation is caused by the secretion of toxins by pathogenic bacteria to stimulate the formation of stratified cells at the base of the petiole, resulting in a large number of early defoliation of apple trees, weakening the tree vigor, has a great impact on apple yield, quality, and the second year of tree vigor, The output also has a great influence. Therefore, the prevention and control of early defoliation is an important task in production. According to observations in production, the incidence and control methods of early apple defoliation in Linyi City are summarized as follows.
First, the incidence of the law
Apple early defoliation, including brown spot, gray spot disease, round spot disease, round spot disease, and spotted deciduous disease. Brown spot mainly damages old leaves and also harms fruits. The wintering of mycelia on fallen leaves was in late June in Linyi City. The onset began, and the onset of the disease began in the July-August rainy season. The deciduous leaf disease is mainly harmful to young leaves, but also harms the shoots and fruits. The mycelium is overwintering on deciduous trees, and the earliest onset was in early May. Round spot disease is caused by wintering in the diseased tree with hyphae or conidia, and spores are transmitted by wind and rain when the ground is wet from May to June.
Second, the cause of the disease
1, related to the number of pathogenic bacteria in winter over the field. The orchard cleared in winter and spring was lighter, the ground was full of weeds, and the orchard with unclear fallen leaves was seriously affected.
2. The severity of the disease is related to the strength of the tree. The management of orchards is good, and those with strong tree vigor are lightly affected. According to investigations at the fruit tree stations in Lixian and Houma, the fruit trees suffered freezing injury in 2002 and 2006, and the orchards with severe frost damage caused early defoliation. All the low-risk, canopy closure, poor ventilation and light transmission conditions, and the management of extensive orchard incidence.
3, Blind use of drugs in production, did not seize appropriate control. Many farmers have neglected the prevention and control of the early stage, the use of drugs is not timely, the improper use of drugs, affecting the control effect.
4. The incidence of disease varies greatly among breeds. According to observations, the strains in the Marshal Department of the Linfen City, Fuji, Jinshuai disease are heavy, and the Qinguan and Jura breeds are lighter.
5. The severity of occurrence is related to the early morning and evening rainfall in spring, the number of precipitation and precipitation. Rainwater is abundant, precipitation is early, early onset, and a large number of conidia can be produced in April-May when it is rainy, and it is conducive to the spread and invasion of conidia. In the spring drought and low rain years, the onset was light and late.
Third, prevention and control measures
1. Strengthen the comprehensive management of orchards. Apply more organic fertilizer, increase phosphorus and potash fertilizer, avoid partial nitrogen fertilizer, improve soil, reasonably water irrigation, timely drainage, scientific pruning, reasonable load, maintain good ventilation and light in the crown of the garden, prevent orchard from being too humid, do a good job of integrated pest management, Strengthen the tree vigor and improve the resistance of the tree.
2, remove bacteria source. After the leaves fall in autumn and winter and after the pruning in early spring, the sick leaves on the trees are completely cut off, the leaves are cleaned, and burned or buried deeply. Before the germination of the fruit trees, combined with the control of rot disease, ring rot disease, spraying of 5 degrees lime sulfur spray or 5% bacteriocin clearing 100 times liquid, eradicate the overwintering germs.
3, spray protection. The protective bactericide is mainly applied at various stages before the onset of the disease, onset of the disease, or after the control of the bacteria to provide protection and prevent the invasion of bacteria. The use of mancozebite and polyoxin alternately works well. If it is rainy in spring, it should be sprayed with protective fungicides in the middle and late May, such as Dasheng M-45, Phoebe, BAK, Xinwansheng. Etc., Mineral-based protective agents mainly include sulfur, lime sulfur, crystal lime sulfur, polysulfide suspension (detergent Wei) and so on.
4, spray shovel removal of fungicides. For various periods such as autumn and winter, early spring gardening and disease prevention and control, such as Bacteroides, 9281, bactericidal, and konjac, etc., are pollution-free biological agents.
5, spray within the therapeutic fungicide. Antibiotic preparations are used in the early stage or before the onset of pathogens, such as Nongkang 120, polyoxin, polyoxin, podophyllotoxin, and jinggangmycin. Organic heterocyclic preparations are used in the disease occurrence period or in various periods, such as ketorol (thiophanate-methyl), carbendazim, triadimefon (triadimefon, chlorhexone), etc., and carbendazim and Bordeaux mixture. Better to use alternately.
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