In recent years, with the increasing area of apple planting, the cultivation management conditions in some production areas have not kept up with the expansion of the planting area, which has led to a rapid increase in the degree of harm of apple astragalus under suitable drought conditions, and has shown an increasingly serious trend. In some counties in the main apple-producing areas of Weibei, Shaanxi, in the period from late May to early June, the rate of newly extracted aphids in some apple orchards reached 40%-70%, and the amount of 100-branch aphids reached 5,000-10,000; some serious orchards reached 70%-100% of the newly extracted aphids in that year, and the amount of 100-000 aphids reached 20,000-30,000, in response to the serious situation of this astragalus, some fruit farmers sometimes sprayed 3-4 times, but still did not effectively control the harm of astragalus. Based on this, on the basis of actual production experience and consulting data, Xiaobian analyzed the main causes and occurrence rules of a large number of astragalus aphids, and combined with these analyses, proposed a set of comprehensive control technology schemes for apple astragalus.
Apple astragalus alias meadowsweet, apple worm, apple aphid, mainly harm the top of the apple branch young leaves and the upper leaves of the plant, the endangered leaves are initially rolled down, and then the leaves will show a downward bend or micro-roll phenomenon, when the aphids are covered with the top of the branches or young leaves, the branches will appear white molting, which will have an immeasurable impact on the growth of new shoots.
Females of apple astragalus: 1.4-1.8 mm in length, yellowish green or yellow in spring, and bright yellow in summer, which is easier to find; nymphs: bright yellow, of which the antennae, feet, abdominal canal and compound eye are black; eggs: 0.57 mm long, oval, black.
The above is roughly the identification of apple astragalus pests and the identification of their harmful symptoms, and fruit growers can judge the approximate number and degree of harm of orchard astragalus pests according to these characteristics mentioned above.
Apple astragalus can occur for about 10 generations a year, overwintering as eggs in bud crevices or cracks in apple branches. Then in the spring when the apple trees bloom and sprout, the apple astragalus eggs begin to hatch, and in early May it reaches the peak of the increase in numbers, and the period from May to June is also the most serious period of apple astragalus harm, from late June to early July, because of the high temperature weather, the number of apple astragalus in the orchard will drop sharply, after entering the rainy season in August, the number of astragalus aphids is almost gone, and then the wintering period of intercropping and spawning begins.
1. High temperature abnormal weather
Historical meteorological data show that the current areas where apple astragalus occur more seriously are mainly those areas that are prone to high temperature and drought, which is one of the reasons why the peak period of apple astragalus hazards is concentrated in May and June every year. Among them, the overall high temperature in spring, the large fluctuation range of temperature and the daily difference in temperature will greatly lay the foundation for the early stage of the onset of apple astragalus.
2. There is a suitable host
The host of apple astragalus is the apple tree in detail, so there are great differences in the probability of occurrence of astragalus depending on the variety of apples. Compared with Qinguan, Gala, New Red Star and other varieties, the probability of astragalus hazards in red Fuji apples with a relatively large planting area in China is greater, which is one of the reasons why the current degree of harm from apple astragalus is relatively large.
3. Inappropriate prevention and control measures
With the prolongation of pesticide use, apple astragalus is more and more resistant to some pesticides, which in turn leads to the gradual loss of the due effect of pesticides that were previously effective in the control of astragalus. For example, in the 1970s and 1980s, as an ideal chemical agent for the control of apple astragalus, it has been used, but the effect has been much worse in the later period; after the 1980s, carbamate and pyrethroid pesticides have been used as an ideal agent for the control of apple astragalus, but in the actual production, it was found that apple astragalus in Shandong and some producing areas in Anhui has a huge resistance to this, and the prevention and control has not achieved the desired effect; since the 1990s, we have mainly used imidacloprid to control apple astragalus. New and efficient pesticides such as acetamid, but with the occurrence of a large number of apple astragalus and the application of a large number of agents, the control effect of apple astragalus in some apple-producing areas in Guanzhong, Shaanxi Province, is also declining. From this point of view, inappropriate control measures are increasingly creating favorable conditions for the continuation of apple astragalus and a large number of hazards.
4. Pests themselves
The breeding method of apple astragalus is parthenogenesis, and the amphoteric reproduction only occurs in the late autumn before wintering, so when the environmental conditions are suitable, the number of apple astragalus can rapidly expand geometrically, thus causing serious harm to apple shoots and other parts.
1. Increase the number of predators
Ladybirds, grasshoppers, aphids, aphid cocoons, aphids, etc. are all natural enemies of apple yellow aphids, and related experimental studies have found that compared with orchards without grass, the number of such insects in grassy orchards can be significantly increased by about 60%, in addition to the fertility of orchard soil and the climatic and environmental conditions in the field have been significantly improved. At present, the types of raw grass used in apple orchards to control apple astragalus are mainly the following: clover, ryegrass and so on.
2. Arrange the yellow plate appropriately
Apple astragalus is a winged aphid, in the process of migration, showing obvious yellowing, so the production can be by arranging yellow plates in the field to hunt. Specifically, in May and June, about 20 yellow plates can be arranged on 1 acre of land, hanging on the outside of the upper main branch of the apple tree. It should be noted that the yellow plate is mainly based on the viscosity of the surface to achieve the purpose of prevention, and most apple orchards tend to have more or less dust substances, which are easy to reduce the killing effect of the yellow plate, and the production can be achieved by regularly observing the sticky effect of the yellow plate, replacing the yellow plate or coating it separately.
3. Chemical control
(1) Overwintering prevention and control: spray 5% diesel emulsion, 40% aphid multi-extinguishing emulsion 1000-1500 times liquid, etc. for prevention and control, in addition to spraying uniformly, no dead angle, but also need to pay attention to the spraying time must be carried out before the apple blossoms.
(2) Prevention and treatment during the onset period: In order to prevent and control the continuous increase in the resistance of apple astragalus, in the production, it can be prevented and treated in accordance with the principle of "insect selection, rotation of drugs, combination of points and surfaces, control of pre-recess, and autumn disability". In the early stage of the onset of apple astragalus, the targeted prevention and control of the severe disease of the branches can be carried out without the method of whole-park prevention and control, and when the peak period of the disease is reached, that is, the period from May to June, according to the insect dynamics in the orchard, the whole garden is sprayed for prevention and control. The agent can choose 5% pyrethroid emulsion 1000 times liquid, 5% acetamidine such as 1000 times liquid, 50% aphid mist wettable powder 2000 times liquid, 10% imidacloprid wettable powder 3000 times liquid, but it should be noted that these agents should be sprayed in rotation, and do not apply the same agent for prevention and control for a long time.
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