In the process of planting green onions, in addition to some common pests and diseases, the emergence of yellow leaves on the leaves of green onions is also a common phenomenon. However, there are many reasons for the stems of the green onions and yellow leaves. The following is a small series to talk with everyone, the reasons for the green onions and yellow leaves and the prevention measures.
First, the soil is acidic, causing the green onions to appear dry
1. Causes: If the application of organic onion is too small, and the fertilizers such as ammonium sulfate and superphosphate are applied in large quantities all the year round, it is easy to cause acidification of the soil. The leaves of the green onions grow thin and become yellow, causing dry tips.
2, prevention measures: the most suitable pH value of green onion growth is 7-7.4, growers should use more decomposed organic fertilizer as the base fertilizer, with other fertilizers, can also use lime to adjust the pH of the soil. Use more biological fertilizers.
Second, the soil is too dry
1, the cause: in the growth process of green onions, do not pay attention to watering, causing soil drought, resulting in green onion leaves turn yellow, dry tip.
2, prevention measures: should be in accordance with the different growth stages of green onions, targeted timely, appropriate amount of water. In the seedling stage of the green onion, the water is properly controlled, and the topdressing and the soil are timely watered in the nutrient growth period to ensure sufficient water supply; the watering should be controlled half a month before the harvest of the green onion.
Third, the weather is high temperature hazard
1. Causes: If the onion is in continuous high temperature, the dry tip of the blade will occur.
2, prevention measures: the green onions, which are cultivated in the open field, should always pay attention to watering and cooling. The cultivation of green onions grown in the greenhouse will enhance the release of wind and prevent the occurrence of high temperatures above 30 degrees.
Fourth, the onion plants are frozen
1. Causes: Green onions are generally susceptible to freezing damage when the temperature is lower than 7 °C. The tip of the onion is damaged by low temperature, and the tip of the green onion will turn white.
2, prevention measures: cultivation of green onions in the greenhouse, to strengthen night insulation.
Fifth, the lack of trace elements
1. Causes: If the green onion grows in the absence of calcium or magnesium and other trace elements, it will easily cause the yellow onion leaves to be yellow.
2, prevention measures: can be appropriate to supplement the trace elements of green onion, foliar spray 0.1%-0.3% calcium nitrate solution.
In addition to the above reasons, the yellowing of the onion leaves may be caused by harmful gases or phytotoxics, pests, etc., and all growers must make rational judgments and correct prevention.
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