Winter shear is an important part of fruit tree field management and should not be underestimated. Jin Peisheng, a senior agricultural technician of the Shaanxi Kiwifruit Industry Comprehensive Service Center, believes that no matter what garden you enter, you must find out the cultivated varieties, the strength of the tree, the fertile soil or the poor, and then budget the next year according to the specific situation. , do your heart.
Go to the old and stay new, go weak and stay strong, update the canopy
If the fruit tree does not have a good canopy, it will not be able to produce high yields, so it is necessary to update the canopy every year. In the natural world, the fruit trees go to the old, stay weak and stay strong, and the natural renewal process is quite slow and takes many years. In most cases, old and weak branches should be removed as much as possible, and new, strong, and prosperous branches should be chosen, and they should not be dragged with water.
Jin Peisheng said that when trimming, the first circle cut off the surrounding and exhausted branches and branches. In the second lap, the old weak and sick branches were removed, and the inside of the tree was pressed inward. On the third lap, the weaker and weaker branches and the less dense branches of the buds in the reserved branches are eliminated, and the reserved branches are better.
However, it is important to remember that the amount of staying branches is small. It can't be like the traditional winter pruning branches, leaving 1.5~2 square meters per square meter, ensuring that the entire rack is well-balanced and has no drawbacks.
High branch down, low branch on stage, layout canopy
Although some individual articles are also very prosperous, the growth point is higher than the frame surface, which will result in inconvenience of tying branches, spraying, pollinating, and combing. It also has an effect on the absorption of sunlight on the normal result branches on the shelf, and must be resolutely removed. Drooping branches, lower branches or low-branched branches have an impact on mechanical or human work, and they are also exposed to light, and these branches are also to be removed.
In general, the main branches and hanging branches of the canopy should be compressed into the 50 cm gold area below the frame surface, so that the branches are evenly distributed, the light is sufficient, the ventilation is smooth, and the coloring is fast and good.
If you make an umbrella frame, then the "Golden Triangle" is very important. It should not be too close to the frame, nor too far. If you plan to make a two-vine frame, you need to go to the head 30~40 cm to lay a good foundation for future high production.
Down the tree, the curved tree is gradually corrected, and the crown is restored.
In general, the branches of the year have been consumed too much due to nutrients, lack of functional nutrition, and many times of germination due to fruit hanging. The branches are short and effective with fewer buds, and the actual value of the reserved branches is not used. For the result of the branch group, there are quite a lot of two wires outside the frame, so it should be completely removed.
In addition, some fruit farmers had no experience when they first built the park. The cement rod is buried in the ground anchor, or it is too shallow or the weight is small and weak, and it is not strong and unreasonable. After a few years, the tree enters the high-yield and fruit-bearing period, especially during the second expansion period. The surface bearing capacity is the greatest. If it hits the wind and the wind is strong, the ground anchor is not pulled up or the cement rod is broken from the ground, and the tree body is also full. Pull down, the wooden pull-down tree is cracked, and many fruit farmers can only change the steel wire after waiting for the fruit. At this time, the tree has grown into a curved rod and hunchback. Some people simply do not go to the tree, so they will work on the winter, so that they will affect the product and quality, so they should slowly correct and gradually correct.
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Bone screws, also known as fracture fixation screws, are commonly used in clinical practice to fix orthopedic implants.
Bone screws are usually used to fix internal fractures or dislocations by directly screing into two different bone blocks or fixing an internal implant such as a bone plate to achieve fracture fixation, position the bone and promote its healing. Bone screws are used in a wide range of areas, including the shoulder, elbow, hip, knee, spine, etc. For example, pedicle screw systems are used for spinal fusion, and compression bone screws are commonly used for foot and ankle surgery or fixation of other fractures under pressure. Similar to traditional mechanical screws, the main structures of bone screws also include nail cap, nail body, and nail tip. Screws can be used to fix bone plates or bone fragments. When used for the former, they are called plate screws, and when used for the latter (to prevent the collapse of bone fragments), they are called positional screws. The latter can be inserted into the plate holes, and can be placed on the bone alone (also known as compression screws). Compression screws can be used to increase interfragment pressure.
(1) The screw cap
The screw cap has three main functions: the first is to optimize the force. The protruding cap makes the contact area between the screw and bone larger, increases the load area, optimizes the local force at the screw insertion site, and reduces the risk of bone rupture caused by excessive stress. The second is the positioning effect. The prominent cap makes the bone nail can only be screwed into a certain depth to prevent the whole bone nail from being screwed into the bone completely. The third function is to provide the position of force application by rotating the force groove at the cap to move the bone nail forward and drive it into the bone. Now, the force groove is mostly inner hexagonal, which does not require axial force to maintain the actuator in the center position and is suitable for a wider range of fractures.
(2) Screw the body
The size of the nail body determines the strength and fatigue resistance of the bone nail. The larger the diameter of the nail body, the stronger the strength will be, and the corresponding fatigue resistance will be better. In addition to the diameter of the nail body, the pitch and tooth depth of the screw body thread are also the key parameters of the nail body design. Different thread design has an important effect on the pressure and occlusal performance of the screw.
(3) Screw tip
Tapping is the process of phalangeal nail cutting thread in the bone. According to the shape of the nail tip, the bone nail can be divided into self-tapping nail and non-self-tapping nail. The nail tip of the self-tapping nail is sharper and can be directly screwed into the bone without pre-drilling. Usually, self-tapping screws are used for Cancellous bone, and the bone is compressed when the screw is inserted, so as to increase the bone density of the occlusal part locally and enhance the occlusal effect. However, when inserting screws in Cortical bone, the screw channel is generally pre-punched, and then the bone screw is screwed. Usually, the self-tapping screw is not directly used to prevent the bone screw from being stuck or damaged because the cortical bone is too hard.
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