What's wrong with yellow beans at the bottom?

The yellowing of bean leaves is often encountered by many vegetable farmers who grow beans, but there are many causes of leaf yellowing, some of which may even lead to extinction if left untreated in time. Now several reasons for the yellowing of bean leaves are introduced as follows. First, the symptoms show two main conditions of yellow leaves of beans. One is the bottom leaf yellowing, easy to fall off, gradually expanding upward, resulting in dead trees. The second is the yellowing of the new leaves at the top, often accompanied by falling flowers and fruits. The third is that the plant will not die, but the leaves of the plant will yellowing in the middle of the vein. Second, reason analysis 1. Bean root rot, commonly known as "red root disease". This is a soil-borne disease, the early pathogen infects the root system, the plant is malnourished, the bottom leaves turn yellow, the plant wilts at noon, recovers sooner or later, and finally leads to death. two。 Lack of trace elements. The leaves at the top growing point appear yellow and white, which is caused by iron and zinc deficiency. The yellowing of the new leaves at the top generally occurs when it is sunny after the shade, poor root growth, the weather changes from cold to warm, and there are too many plants bearing in the early stage. 3. The plant is not growing well. This situation will not cause the death of the plant, mainly because of the poor growth of the plant, which leads to the yellowing of the middle and lower leaves and veins, which is easy to cause premature senescence. For example, high temperature in the greenhouse, root dysplasia, root injury, unscientific fertilizer and water supply and so on can cause a similar situation. Third, prevention and control methods 1. Bean root rot can be irrigated with medicament. You can choose the medicament: carbendazim thiram (allicin) + carbendazim + oleic acid copper root irrigation. two。 Foliar spray can be applied in bad weather and in the middle and later stages of plant growth: amino acid foliar fertilizer (chelating various trace elements such as boron, calcium, magnesium, iron and zinc) can effectively relieve the yellowish-white new leaves at the top. 3. Enhance plant resistance, cultivate strong roots, water reasonably with fertilizer, prevent yellowing in the middle of leaf veins, resulting in premature senescence of leaves.