What causes yellow leaves and dead seedlings in soybeans? A full analysis of prevention and control methods

Farmers often encounter yellow leaves and dead seedlings when growing soybeans, which seriously affects soybean yield and causes huge economic losses for growers. So what causes yellow leaves and dead seedlings in soybeans? How should they be prevented and controlled? Let's take a look at the detailed introduction.

1. Disease

When soybeans are infected with top dieback at the seedling stage, brown ring spots appear on the cotyledons, the growing points become necrotic, and in severe cases the whole plant dies. In plants infected before flowering, the internodes lengthen, the terminal buds turn brown, and the plants become brittle and prone to lodging. In plants infected after flowering, the leaves fall off easily, fewer pods are set, the pods and seeds develop poorly, maturity is delayed, and the plants remain green before harvest.

Prevention and control measures: When plants are infected, promptly pull out the diseased plants to prevent the disease from spreading. For lightly infected plants, spraying with dufulin and chlorothalonil gives good results.

2. Insect pests

Soybean cyst nematode can cause dead seedlings. When seedlings are damaged, the leaves change, development is slower, and in severe cases the plants wither and die. When adult plants are affected, growth is poor and the plants are stunted, the leaves turn yellow from the bottom upward, flowering is delayed, and the pods and seeds grow poorly and are darker in color. When the diseased plants are pulled out, the root system is found to be poorly developed, with few root nodules, and many soybean cyst nematodes attached to the roots.

Prevention and control methods: Apply more organic fertilizer to improve soil fertility and promote soybean growth. Water timely to keep the soil moist; a dry soil environment is extremely favorable for the reproduction of soybean cyst nematode. For affected fields, a low-concentration omethoate emulsion can be sprayed on the base of the stems.

3. Nutritional imbalance

In fields lacking fertilizer, fields where a single fertilizer is applied excessively, or fields with severe drought, the plant leaves show various degrees of yellowing and wrinkling, plant growth also slows, and in severe cases the plants die from nutrient deficiency.

Prevention and control methods: Fertilize scientifically and reasonably to ensure sufficient soil fertility and promote soybean growth. For fields lacking fertilizer, a low-concentration potassium dihydrogen phosphate solution can be sprayed, which can relieve or eliminate the symptoms and allow soybeans to grow normally.

4. Herbicide phytotoxicity

When weeding, problems such as improper timing of herbicide use, excessive dosage, improper herbicide combinations, and repeated spraying can all cause herbicide phytotoxicity, leading to yellow leaves in soybean plants and, in severe cases, dead seedlings.

Prevention and control methods: The use of herbicides must be strictly regulated. After phytotoxicity is found, water promptly to reduce the concentration of the chemical, and spray foliar fertilizer and plant growth regulators to relieve the phytotoxicity.

The above is an introduction to the causes of yellow leaves and dead seedlings in soybeans and the prevention and control methods. We hope it helps you. For more related knowledge, please follow us.