Wang Guiren A: According to the symptoms described by this friend, we should judge the current yellow beans, mainly the following:
1. The root system is not good, affecting plant growth. The specific reason is roots. The recent increase in rain, hot weather, or increased watering, in this case, often appear yellow leaves. Kidney beans are very strict on the moisture requirements, causing water to fall and fall out of the general assembly. When the humidity is high, it can also cause roots to be rooted, causing red root disease and yellow leaves. We should see the wet see dry, see the situation watering, frequent rain water drainage.
2. It may be nematode damage. The nematode is not a root-knot nematode but a subterranean nematode, which is mainly responsible for the junction between the lateral root and the main root, but does not produce root nodules. The resulting condition is that the base of the stem is rough, the epidermis is cracked, and the roots are rotted and decayed. Remedy: Strictly control watering, not just watering the sky, and water according to the principle of “watering without wateringâ€. For various diseases to be prevented as soon as possible, for the nematode, use Volvo or Bromochlor to control, you can also Shi Jian Jian anti-nematode fertilizer.
3. Disease caused by yellow leaves. Kidney bean bacterial disease, also known as "fire disease," is a serious threat in high temperature and rainy years. The disease mainly damages leaves and vines to yellow the leaves. The cotyledon of the diseased seedling shows a reddish-brown ulcer, which then spreads to the base of the first true leaf petiole or the node where the leaflet is formed. The water spot is first spotted, and the reddish-brown ulcer appears. The disease spot circles around the stem one week and the seedlings are cut off. . Damage to adult plants begins at the tip of the leaf or leaf margin. It begins with water-stained dark green patches, and then spreads into irregular brown patches with yellow halos around it. The lesions commissure and the whole leaf darkens withered. The lesions on the stems are similar to the leaves, and are slightly sunken. The stems and leaves are yellowed and dead around the stem.
Chemical control: 200 grams of copper rosinate and 400 grams of blue powder carbendazim are used for prevention and control, and the prevention and treatment uses 200 ml of rice seedlings +1.6 million units of agricultural streptomycin 120 to 150 grams, sprayed once every 7 to 10 days, and even sprayed 2 ~ 3 times.
4. The reason for trace elements. The newly emerged new leaves are completely yellow, but the leaves are neat and the nicks are obvious. One reason may be that the base fertilizer contains excessive amounts of phosphate fertilizer, resulting in the inhibition of iron absorption by the plants. Only iron deficiency can fully yellow the new leaves. In addition, excess of boron and zinc, too much water will inhibit the absorption of iron. Solution: You can spray leaf fertilizer containing iron, such as green faster, can also be rushed with water ferrous sulfate.
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