Maize rough disease is a viral disease transmitted by Laodelphax striatellus. The incidence of the disease: the occurrence of the disease is closely related to the density of the gray planthopper, the former crop, the sowing date, and the cultivar. Laodelphax striatellus is an effective mediator for spreading corn rough disease. The amount of gray planthopper in the field is directly related to the occurrence of corn rough disease. Wheat is the main host of the gray planthopper, and the planting area is large. After the end of May. As the wheat matures, the gray planthopper migrates out of the wheat field and enters the summer sowing crops such as corn to take food. At this time, in the sensitive period of corn (before 10 leaves), the virus disease is transmitted. Therefore, peas, garlic, barley, rapeseed and waxy corn, due to the early sowing date (in the middle and late May), often have a serious incidence; the wheat sowing corn has a late sowing period (in the middle of June), the sensitive period and the gray planthopper occur. The period is staggered and the incidence is lighter; according to the Chinese Pesticide Network , different varieties of maize have different disease resistance to corn rough disease, such as Denghai No. 3, Xianyu 335, Ludan 50, Zhongyu No. 4 and Suyu No. 9 The disease has certain disease resistance and the incidence is mild.
Control strategy: Due to the strong activity of Laodelphax striatellus on corn and the lack of resistant varieties, it is necessary to adopt agricultural measures such as adjusting sowing date and planting disease-resistant varieties in the prevention and control, while insisting on “cutting off the poison chain, The prevention and control strategy of controlling insects and diseases, grasping the seed dressing of corn seeds and the control of gray planthoppers in corn seedlings, controlling the number of gray planthoppers and reducing the harm of poisoning.
Control measures: adjust the corn sowing period, avoid the peak period of the gray planthopper poisoning - the corn seedling period to the 10 leaf stage is a susceptible stage, can expand spring corn and summer corn, do not grow semi-summer corn, make corn easy The sensitive period of the disease is staggered with the poisoning period of the Laodelphax striatellus; for the pea 茬, garlic 茬, barley glutinous rice, rapeseed 茬 corn, without affecting the post-crop crop, it can be postponed until the wheat harvest; planting disease-resistant varieties - - Can promote the cultivation of disease-resistant varieties such as Denghai No. 3, Xianyu 335, Ludan 50, Zhongyu No. 4; medicinal seed dressing - before planting, use corn seed coating agent No. 17 according to pesticide seed ratio 1:50 coating or use 40% methyl isothiophos emulsifiable concentrate is 0.2% seed dressing, which can play a role in pest control; seedling prevention and control - catching the key period of corn seedling stage, in front of corn 6 leaves Use 10% imidacloprid powder 10g/mu or 3% acetamiprid emulsifiable concentrate 10ml/mu, spray 30kg with water to control the gray planthopper, and pass with 1.5% plant disease II, 20% virus A and other plant virus passivation Mixed spray; combined with seedlings, seedlings to remove weak seedlings.
NSK manufacture a full range of deep groove ball bearings. These bearings are the most common type and are used in a wide variety of applications.
Single-Row Deep Groove Ball Bearings
Pressed Steel Cages
Single-row deep groove ball bearings are the most common type of rolling bearings. Their use is very widespread.
In addition to open type bearings, these bearings often have steel shields or rubber seals installed on one or both sides and are prelubricated with grease. Also, snap rings are sometimes used on the periphery. As to cages, pressed steel ones are the most common.
For big deep groove ball bearings, machined brass cages are used.
Machined cages are also used for high speed applications.
Extra Small Ball Bearings and Miniature Ball Bearings
Miniature and instrument ball bearings can be divided into two basic types, deep groove and angular contact. The first (deep groove) can be further divided into the following five classes depending on their design details:
Standard type
Flanged outer ring
Extended inner ring
Expanded type in which one ring has a radial thickness that is larger than normal compared with the bearing width.
Thin section type in which both rings are extra thin in the radial direction. They can also be classified as: open, shielded, or sealed.
Maximum-Type Ball Bearings
Maximum-Type ball Bearings contain a larger number of balls than normal deep groove ball bearings because of filling slots in the inner and outer rings. Because of their filling slots, they are not suitable for applications with high axial loads. types of bearings have boundary dimensions equal to those of single-row deep groove ball bearings of Series 6200 and 6300 respectively. Besides the open type, ZZ type shielded bearings are also available. When using these bearings, it is important for the filling slot in the outer ring to be outside of the loaded zone as much as possible. Their cages are pressed steel.
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