Causes and Control Methods of Yellowing Spinach Leaves
Spinach is one of the most common vegetables, native to Iran, and is rich in carotene, vitamins and various other nutrients, with high nutritional value. Spinach is grown in most parts of China, is relatively cold-tolerant and highly adaptable, but many farmers who have grown spinach have encountered the sight of spinach leaves starting to turn yellow as it grows. What is going on here? Below, QinNong Net introduces the causes of yellowing spinach leaves and the corresponding control measures.
1. Causes of yellowing spinach leaves
There are mainly four causes of yellowing spinach leaves, including normal metabolism, soil problems, fertilizer problems, water problems, etc. Below, QinNong Net introduces them in detail:
1. Normal growth assessment: if new roots grow from the leaf axils of the lower leaves of spinach, then the leaves turning yellow is a normal phenomenon, as this is the spinach's own metabolism.
2. Soil problems: if no new roots grow from the leaf axils of spinach but the leaves turn yellow, it is mostly due to raw soil, poor air permeability, etc. causing poor growth of spinach and the appearance of yellow leaves. At this time, the soil should be turned over to increase air permeability.
3. Fertilization problems: spinach itself has a ratio of 2:1:3 for the three major elements nitrogen, phosphorus and potassium, which shows that it needs more nitrogen fertilizer and potassium fertilizer, but the amount cannot be increased at will for high yield, nor should a certain fertilizer be applied excessively. In addition, on soil lacking trace elements such as iron, zinc, manganese and boron, yellow leaves, small leaves, soft rot and other phenomena will also occur, and these can be solved by spraying spinach foliar fertilizer in the later stage.
4. Excessive water: watering spinach too much will cause root hypoxia, leading to poor growth and yellow leaves. Generally, for watering, a chopstick can be inserted into the soil to see whether the root area of the spinach is short of water; as long as it is moist, there is no need to water again.
2. Control measures for yellowing spinach leaves
There are mainly two preventive measures for yellowing spinach leaves. Here, QinNong Net gives everyone a brief introduction from the agricultural and chemical aspects respectively.
1. Agricultural measures: use seeds harvested from disease-free plants. Lay and hang silver-gray film strips in the field to repel aphids. Clean the field in time, eradicate field weeds, and pull out diseased plants in time. Choose to plant in plots with good ventilation and far from radishes and cucumbers. Sow at the right time and avoid sowing too early. In case of spring drought or autumn drought, water more, which can reduce disease incidence. Apply sufficient organic fertilizer, increase the application of phosphorus and potassium fertilizers, and enhance the disease resistance of the host. For aphid control, aphids must be controlled at the seedling stage, especially before winter.
2. Chemical control: at the early stage of disease, spray 1.5% Zhibingling emulsion 1000 times dilution, or 0.5% Kangduji No. 1 aqueous solution 300 times dilution and other agents. For downy mildew and anthracnose, at the early stage of disease, 75% chlorothalonil 600 times dilution, 25% metalaxyl 700 times dilution, 40% fosetyl-aluminum wettable powder 300 times dilution, etc. can be sprayed for control. For viral diseases, in addition to crop rotation, aphids and other virus-transmitting vectors should also be controlled in time. During the peak period of aphids, 10% imidacloprid 2000 times dilution or 10% nitenpyram 3000 times dilution can be sprayed for control.
The above are the causes of yellowing spinach leaves and the related control methods. After discovering yellowing spinach leaves, everyone should actively look for the causes, then adopt corresponding control measures, implement the concept of “prevention first, treatment as supplementary”, and produce healthy and high-quality spinach varieties.