What are the reasons for the yellowing of citrus trees? What are the methods of prevention and control?

Citrus is one of the fruits that people love to eat very much and is very common. But in fact, citrus cultivation is not easy, easy to appear yellowing phenomenon. So orange tree yellowing is what causes, what are the ways to prevent it? About these soil drift nets, we should briefly introduce them to growers, hoping to bring help to growers.

1. Causes of yellowing of citrus trees

1. Waterlogging of soil

When some citrus planted in low-lying areas, due to the high water level under the land, and then encounter rainy season, it is easy to make citrus roots long-term waterlogging abuse, resulting in poor root absorption capacity. Citrus trees are in a yellowing state, which is called "senescent trees". Also, the soil in the south is generally acidic, and citrus roots cannot effectively absorb nutrients, which directly leads to the reduction of citrus branches and leaves growth, and the tree body is in a yellow and stagnant state for a long time.

2. Phytophthora in soil

Orange tree yellowing is also due to the rampant activities of harmful microorganisms such as Phytophthora in the soil, which directly leads to root rot and other phenomena, losing the absorption capacity of citrus roots. Orange trees are in a semi-hungry state for a long time, yellowing will naturally occur. There is also the use of biological fertilizer, but not decomposed, when the raw fertilizer dissolved fermentation of harmful microorganisms, resulting in damage to the root system, especially excessive fertilizer or high concentration, especially easy to produce rotten roots phenomenon. And it is difficult to recover, which leads to slow growth of citrus trees, and few branches and leaves, in the long run will appear tree yellowing.

3. Improper application

In addition, improper application of pesticides to citrus trees, such as large concentrations of pesticides, especially when the temperature is too high, causes citrus trees to fall leaves or mottled yellow leaves, resulting in orange trees as a whole yellowing. Citrus tree root knot nematode parasitizes under the root bark, mainly harming the root of citrus tree, causing the root tissue to divide due to root knot nematode, forming nodules of different sizes, reducing fibrous roots, finally rotting old roots due to nodules, root bark mildew, weak attraction ability, nutrition in the soil can not be absorbed, long-term such will appear yellowing, when yellowing reaches a certain degree, it will directly affect the yield.

4. Improper use of herbicides

In order to save labor and time, some growers use herbicides in large doses, drug residues will accumulate continuously in the soil, destroy the physical and chemical properties, aggregate structure and porosity of the soil, kill beneficial microorganisms, affect the absorption of citrus roots, and yellow will occur naturally after a long time. Finally, the whole citrus tree branches and leaves are yellowed, and its symptoms are similar to the yellowing type caused by root-knot nematodes, which makes it difficult to distinguish.

II. Countermeasures for orange yellowing

1. Soil improvement

Creating a good root environment is the most important. At the same time, timely drainage and irrigation, especially in rainy seasons, special attention should be paid to the roots of citrus trees to observe whether soaking phenomenon has been caused, and at the same time, ditches should be opened to completely eliminate the accumulated water at the roots of citrus trees, so as to prevent soil hypoxia and root rot. For citrus trees to be patient and meticulous, do observe at any time, there are problems solved in a timely manner. This can effectively prevent citrus tree yellowing.

2. Scientific fertilization

Scientific fertilization should be changed to topdressing methods, dry fertilization, raw fertilization, water fertilization and decomposition fertilization. Pay attention when opening fertilizer ditch, do not reach many roots, sow outside the drip line of tree tray in adult fruit garden, and remember to mix well with soil, and then cover and loosen soil. If the weather is dry, irrigation should be timely after fertilization. The fertilizer types are mainly organic fertilizers with various elements, and biological organic fertilizers can also be used to add trace elements and fertilize together. In this way, the disease caused by deficiency and fertilizer damage can be alleviated. There is also the tree yellowing caused by root-knot nematodes. You can use Kexiandan granules and sprinkle them around citrus roots. This will kill root-knot nematodes and effectively reduce the harm of root-knot nematodes in the soil.

3. Standardize the use of pesticides

Citrus tree standard use of pesticides, especially pay attention to high temperature and control of young shoots and leaves, especially the prescribed citrus tree prohibited use of pesticides, according to the instructions to prohibit the use of special attention to agricultural materials market a variety of pesticides, can not be easily used at will. It is more important to avoid the use of counterfeit pesticides, and it is not possible to add various pesticides at will and mix them. So as not to cause damage to citrus leaves, and the formation of yellowing. Only by strengthening cultivation management and improving tree resistance can we effectively control citrus yellowing.

I don't know if it is helpful for growers to introduce so much. I hope that under scientific management, growers can have a good harvest.