What is soybean yellowing and how to prevent it?

What is soybean yellowing and how to prevent it? There are several main reasons for soybean yellowing: first, soybean cyst nematode disease. The disease is mainly distributed in soybean continuous cropping plots for many years and areas with low groundwater level. After the disease in the seedling stage, the leaves were yellowish brown, the growth was slow, and when the disease was serious, the whole plant died; in the adult stage, the plant became dwarfed, the leaves yellowed from bottom to top, the flowering period was 5-10 days later than that of the control, the pods were less, the seeds were not full and the color was dark. Sensory recognition: the root system of the plant is underdeveloped, there are many whisker roots, few root nodules, and there are a lot of cyst nematodes (small yellow granules) on the roots. Prevention and control methods: rotation and stubble change to prevent drought. The affected field can be sprayed roughly at the base of the plant stem with 1000 times of omethoate. Note that the use of fog control effect is poor. The second is virus. It is mainly distributed in the fields where aphids are heavy. The plant is caused by aphid-transmitted virus disease that causes leaf shrinkage, yellowing, shortening of internodes and dwarfing of plants. Control method: when aphids occur in summer soybean field, spray 40% omethoate 1000-1500 times, or enemy kill and quick kill 5000-10,000 times. Third, bean stalk fly disease. It mainly occurs in the field or continuous cropping land where there is more application of immature organic fertilizer. It is susceptible to disease at seedling stage, which shows that the lower leaves of the plant are normal and the upper leaves are all yellowed. Sensory recognition: peeling off the rhizome, there are bean stalk maggots and maggot dung in the culm. Control method: 1000 times of omethoate or phoxim was sprayed at seedling stage and flowering stage, and the control effect was better. The fourth is nutritional disorder. Mainly occurred in the lack of fertilizer fields, or partial application, single application of a certain nutrient element chemical fertilizer or severe drought in the high land. Different degrees of leaf yellowing, shrinkage and growth retardation occurred in the plant. Control methods: spraying Huimanfeng 50ml / mu or Opal, Lvfeng 95 plus 100g potassium dihydrogen phosphate per mu to spray 30kg 50kg of water, the symptoms can be relieved or disappeared, and the plant can resume normal growth. The effect of using fog method is better. Click to see more soybean planting techniques click to see more food crop planting techniques