Yellowing disease is the phenomenon of yellowing and even whitening of the fruit in the leaves of the fruit tree during the growth process due to the obstruction of chlorophyll synthesis. It is found in the main apple producing areas in Guanzhong area of ​​Shaanxi. Other crops such as peaches, apricots, plums and other fruit trees also occur.
In 2003-2004, the incidence of yellowing disease was large, resulting in bad taste, low sugar content, low hardness, and poor storage stability, which greatly affected the economic income and production enthusiasm of the farmers. In response to this situation, fruit growers have adopted various methods such as foliar spraying, irrigation and hanging bottles, but most of them have had little success.
The company has carried out some work on its causes and corrections. It now makes a brief summary of the results and results achieved, and hopes to exchange ideas with the majority of agricultural technicians.
The formation of yellowing disease on the one hand is due to root or leaf damage or infection by pathogenic bacteria. The common cause is the chlorophyll synthesis disorder. We have selected dozens of sample plots of severe yellowing disease in orchards and vegetable greenhouses in some areas of Guanzhong, and adopted soil samples in three phases of dormancy, fruit setting, and fruit swelling in one growth period. At the same time, we adopted the same type of soil samples. The normal orchard soil was used as a comparison to determine the main nutrient elements such as nitrogen, phosphorus and potassium, organic matter, and trace elements such as iron, boron, zinc, and manganese.
After analysis, it was found that most of the yellowing diseases were caused by absolute or relative malnutrition of certain nutrient elements, and the occurrence of malnutrition mainly had two points:
First, the absolute lack of nutrients: crops of iron, boron, calcium, zinc and other elements in addition to a small amount of fertilizers outside the roots, mainly obtained from the soil through the roots, if the lack of elements in the soil, will inevitably lead to insufficient supply. With the widespread application of chemical fertilizers in agricultural production, land yield has increased sharply. However, micro-fertilizer has not received the same attention as a large number of elements. As a result, blindly replenishing large amounts of elements and ignoring trace elements will inevitably lead to depletion of trace elements in soil. Sex consumption, causing a lack of ingredients.
Second, the relative obstacles of nutrient elements: the so-called relative obstacles means that the absolute value of certain nutrients in the soil is not low, but because other factors lead to crops can not normally absorb and use. That is, the soil does not lack the above-mentioned nutrient elements, but it cannot absorb the problems in the utilization and utilization links.
In addition to malabsorption caused by the morbidity of the root system, the soil nutrient environment is the main cause of malabsorption. Its impact is mainly manifested in the following aspects:
(1) Fixation: Iron, magnesium, manganese and other elements easily form phosphate-insoluble, water-soluble precipitates in the soil during the diffusion process, and are difficult to absorb for crops. In recent years, many fruit growers have been pursuing high yields and applying a large amount of phosphate fertilizers that can promote reproductive growth, leading to a large increase in the concentration of phosphate in the soil, making the fixation more serious. The kiwifruit garden of Jiangjiazhai Jiang of Yangling Demonstration Area in Shaanxi Province has been plagued by yellowing disease for many years. When the author investigated the garden, the available phosphorus content in the garden was as high as 280 mg/kg, which was more than five times the normal value, and Also plans to top 100 kg superphosphate. The author suggested that he should save the two bags of phosphate fertilizer that he plans to pursue. Other management measures were carried out according to the original plan. A few months later, Jiang called and said that almost every fruit tree was yellow in previous years, but almost every tree was not yellow this year. Now.
(2) Hysteresis: Boron, iron, manganese and other elements move slower in the soil than nitrogen, potassium, and other nutrients. That is, they take a long time to reach the root system. This is because their movement in the soil is hindered by many factors. Among them, the soil texture is the main factor, and the soil with high PH value, strong viscosity, and easy-to-consolidate soil has a greater impediment to it. An orchard with a severe yellowing disease is often low-lying and has a strong soil viscosity. This is the reason for this. In addition, large-scale application of chemical fertilizers can cause soil compaction.
(3) Competition: The absorption of nutrients by fruit trees is mainly carried out through ion exchange, and the exchange capacity of certain crops (related to the roots of fruit trees, soil texture, irrigation conditions, etc.) is certain, and some of the slower moving speeds in the soil When there are too many elements in competition with the trace elements, it is easy to cause nutritional disorders. In actual production, we measure the soil of fruit trees with obvious calcium-deficiency disorders, and the calcium content of them often reaches 4000 mg/kg or more, which is not lacking. However, the calcium content of the leaves is often insufficient. This phenomenon is mainly The combination of competition and hysteresis.
In fact, the absorption of microelements in fruit trees is often the result of the long-term effects of these three factors. These three kinds of effects are objective, but wild fruit trees rarely suffer from yellowing, which is due to the regulation of nutrients by the soil and the fruit tree's own regulation and absorption of nutrients. The two work together to meet Fruit tree nutritional balance needs. However, after the adoption of human cultivation, people rely on the improvement of fruit varieties and the use of large amounts of chemical fertilizers to achieve high-quality and high-yield purposes. However, the application of chemical fertilizers is difficult to achieve in a reasonable, appropriate, and timely manner, resulting in localized concentrations of one or more nutrients. Too high will directly affect the normal flow and absorption of other nutrients, and even lead to soil compaction and texture destruction. As time passes, the limited self-regulatory capacity of soil and fruit trees will be destroyed, and yellowing disease will also occur. Based on the above principles, we have targeted targeted treatments for fruit yellowing in some places.
In summary, the formation of yellowing disease is a long-term process from quantitative change to qualitative change. The correct correction method should also be stepped and organized and slowly corrected. We believe that the principle of "mainly treating the disease and treating both the symptoms and the symptoms" should be adopted to improve it year by year.
The unreasonable indiscriminate use of chemical fertilizers is the "origin" of the formation of yellowing disease. It should start with rational and balanced fertilization to cure the "origin." First, we need to balance the formula fertilization, synthetic crops need fertilizer characteristics, soil nutrient content (including large, medium and trace elements), soil texture, climatic conditions, the last quarter of the mu yield and other factors to get a correct and detailed fertilization program. Which kind of fertilizer to apply, how much to apply, when to apply, how to apply everything. Several kinds of chlorophyll synthesis related to the lack of trace elements is the "target" of the occurrence of yellowing disease. On the basis of a permanent cure, it is regularly supplemented by nutrients, plant physiological regulators and absorption enhancers. Equipped with drugs to improve the immediate nutritional status of the crop. In this way, after a scientific and comprehensive correction, good results can be achieved. Although it takes a long period of time, both the symptoms and root causes have a huge overall benefit.
Yangling Taide Agricultural Technology Co., Ltd.
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