What is the reason why the old leaves of beans planted on the balcony are dry and yellow

1. Symptoms.

There are two main cases of carob yellow leaves. One is that the bottom leaves are yellow, easy to fall off, and gradually expand 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 does not die, but the leaves and veins of the plant are yellowed in the middle.

2. Cause analysis.

1. Carob root rot, commonly known as "red root disease". This is a soil-borne disease, in which the root system is infested by pathogens in the early stage, the plant is malnourished, the bottom leaves are yellow, the plant wilts at noon, recovers in the morning and evening, and finally leads to death.

2. Lack of trace elements. The leaves at the top growth point appear yellowish-white, which is caused by iron and zinc deficiency. The yellowing of the new leaves at the top generally occurs when the new leaves are sunny after the shade, the root growth is poor, the weather changes from cold to warm, and the early plant bears too much fruit.

3. Poor plant growth. This situation will not cause the plant to die, mainly because the plant is not growing well, resulting in yellowing in the middle of the middle and lower leaf veins, which is easy to cause premature senescence of the plant. For example, the temperature of the shed is too high, the root system is underdeveloped, the roots are damaged, and the fertilizer and water supply is not scientific.

3. Prevention and control methods.

1. Carob root rot can be irrigated with pesticides. Choice of potion: carbendazim. Formeidi (allicin) + oxafen + copper pine acid root irrigation.

2. Foliar spray can be used in bad weather and in the middle and late stages of plant growth: amino acid foliar fertilizer (chelating various trace elements such as boron, calcium, magnesium, iron, zinc) can effectively alleviate the yellowish white of the top new leaves.

3. Enhance plant resistance, cultivate strong root system of plants, and use fertilizer reasonably to prevent yellowing in the middle of the leaf veins, resulting in premature leaf aging.