What is the yellow leaf of soybean before flowering?

In recent years, yellow leaf disease has occurred widely in legume crops such as soybeans. If it is not controlled in time, it will cause serious harm to crop growth. Such as early onset, yellowing leaves, short plants, no pods. Mid-term disease, even if pods, there are no seeds, even if there are grains, but also shrivelled, resulting in a serious reduction in production or no harvest.

The reasons are as follows: first, long-term application of chemical fertilizer, the reduction of farm manure, resulting in soil consolidation. Second, in recent years, it is common to use combine harvester and burn wheat stubble, which destroys the surface structure of the soil. Third, the symptoms of element deficiency are serious, such as iron, calcium and so on. Fourth, bacterial infection is the main cause of yellow leaf disease.

The types of yellow leaf disease can be summarized as: element deficiency type, bacterial type, sugar deficiency type and so on. Long-term continuous rain and poor photosynthesis lead to sugar deficiency in plants; the emergence of yellow leaves leads to premature senility, defoliation, defoliation and yield reduction.

Control measures: (1) apply more farm manure and improve soil structure; (2) apply balanced formula fertilization and supplement trace elements (zinc, iron, sulfur, calcium); (3) ban wheat stubble and protect soil structure; (4) spray micro-fertilizer when yellow leaf disease occurs. 2 taels of zinc sulfate per mu, equipped with a bag of fungicide "Baozhida" Plant regulator "Lufeng 95" or "Sanriling" or "Huimanfeng" (any one), eat brown sugar 22 taels, turn green three days after spraying and return to normal.