Peanut Stem Rot: Damage Symptoms and Control Methods Explained

Peanut stem rot, commonly known as "rotten neck disease," is distributed in all peanut-growing regions across the country. It generally occurs in the middle and late stages. After infection, plants quickly wither and die, and the pods often rot or the kernels fail to fill out, causing serious losses. The disease incidence rate in ordinary fields is 20-30%, and in severe cases reaches 60-70%. Especially in peanut plots that have been continuously cropped for many years, plants may even die in patches. Now let us take a look at the control methods for peanut stem rot!

Damage Symptoms of Peanut Stem Rot

The pathogen invades the plant from the cotyledons or young roots, producing yellow-brown water-soaked lesions at the root crown, which later turn dark brown and cause rotting of the root tissue. In moist conditions, the diseased area produces pycnidia (small black raised spots), the epidermis of the diseased area peels off easily, and the fibrous tissue is exposed. In dry conditions, the epidermis of the diseased area becomes sunken and tightly adheres to the stem. After infection at the mature plant stage, the entire plant dies within about 10-30 days. The affected site is mostly at the stem base near the ground, and sometimes the main stem and lateral branches die off in stages.

Conditions for the Onset of Peanut Stem Rot

The pathogen mainly overwinters on seeds and diseased plant residues in the soil, becoming the source of infection for the following year. If diseased plants are used as feed or the feces of livestock fed with pod shells, as well as farmyard manure composted with mixed diseased residues, the disease can also spread. In the field, transmission is mainly through rainwater runoff, followed by strong wind, though pathogens carried during farming operations can also spread the disease. In rainy and humid years, especially when rain occurs during the harvest season, the harvested seeds have a higher rate of carrying the pathogen. Therefore, they are not only the main spreaders of the disease but can also be transmitted over long distances through the introduction of seeds.

Agricultural Control of Peanut Stem Rot

1. Select superior varieties: Yuhua No. 7, Yuhua No. 8, Yuhua No. 9, Luhua No. 11, etc. are all good varieties.

2. Manage seeds well: Peanuts used as seeds should be harvested promptly, dried promptly, and stored in a ventilated and dry place to prevent moisture and mold. Before sowing, seeds should be carefully selected and sun-dried to promote germination and emergence.

Chemical Control of Peanut Stem Rot

1. Seed soaking with chemicals: Use 50% carbendazim wettable powder plus Xin Gao Zhi Mo (New High-Fat Film) at 5% of the seed amount, mix with 1.5-2 kg of fine soil, apply water and scatter the chemical in layers, then mix well and sow after sprouting. This can repel underground pests and diseases, isolate virus infection, without affecting the germination and imbibition function, strengthen respiration intensity, and improve the seed germination rate.

2. Chemical spraying: During the growing period, use 50% carbendazim wettable powder at 600 times dilution or 70% thiophanate-methyl plus 50% carbendazim powder for spraying. Spray once after full emergence of peanuts and once before and after flowering, or spray 1-2 times in the early stage of disease onset. Using Previcur at 800-1000 times dilution for spraying can also simultaneously control peanut root rot, damping-off, leaf spot, etc.

How to control cowpea basal rot? Control methods for cowpea basal rot

Cowpea basal rot, also known as damping-off, mainly threatens crops such as cowpea, common bean, cotton, peanut, and sweet potato, causing diseased seedlings to grow slowly or wither and die. So how to control cowpea basal rot? What are the control methods for cowpea basal rot?

How to control cowpea basal rot? Control methods for cowpea basal rot

1. Before sowing or transplanting, or after harvest, clear weeds in the field and surrounding areas, and burn them in a centralized manner or compost them; deep plow the land to destroy stubble, promote the decomposition of diseased residues, and reduce pathogen and pest sources.

2. Choose well-drained, high and dry, sunny plots for seedling raising. Use pathogen-free new soil for the seedbed, and fully sun-dry the seedbed soil before raising seedlings.

The seedbed should be selected in a place sheltered from wind, sunny, high and dry, and convenient for drainage and irrigation; choose disease-free soil for nutrient soil; the organic fertilizer in the nutrient soil must be fully decomposed; the nutrient soil must be sun-dried for at least three weeks before use.

3. Rotate with non-grass-family crops, with paddy-upland rotation being the best.

4. Choose disease-resistant varieties, and use disease-free, coated seeds. If not coated, seeds must be sterilized with a seed dressing agent or seed soaking agent.

5. Choose fields with convenient drainage and irrigation, dig drainage ditches well, lower the groundwater level, and achieve no standing water after rain stops; after heavy rain, promptly clear the ditch system to prevent moisture retention and reduce field humidity. This is an important measure for disease prevention.

6. Sow at the appropriate time and early, transplant early, thin seedlings early, cultivate soil early, fertilize early, and timely carry out intertillage and soil cultivation to cultivate strong seedlings.

7. For seedling raising and transplanting, spread a thin layer of medicated soil at the bottom of the seedbed, cover with medicated soil after sowing, and spray once with an insecticidal and sterilizing agent before transplanting. This is the key to disease prevention.

8. For fields with high soil pathogen levels or severe underground pests, scatter or apply in furrows sterilizing and insecticidal medicated soil before sowing.

9. Apply compost fermented with enzyme bacteria or decomposed organic fertilizer, do not use pathogen-carrying fertilizer, and the organic fertilizer applied must not contain plant diseased residues.

10. Adopt soil testing and formula fertilization technology, appropriately increase the application of phosphorus and potassium fertilizers, strengthen field management, cultivate strong seedlings, and enhance plant disease resistance, which helps reduce the occurrence of diseases...

11. Plastic film mulching cultivation can prevent soil pathogens from harming the aboveground parts of plants.

12. Avoid pruning in cloudy and rainy weather; timely control pests to reduce plant wounds and reduce the pathways of pathogen transmission; timely control when disease occurs, and remove diseased leaves and diseased plants, take them out of the field and burn them, and apply chemicals or quicklime to the diseased holes.

13. For greenhouse cultivation, during the summer fallow period, irrigate inside the greenhouse, cover the ground with plastic film, close the greenhouse for a few days, and use high temperature to sterilize;

14. During high temperature and drought, irrigate scientifically to increase field humidity and reduce the damage and virus transmission by aphids and small brown planthoppers. Continuous irrigation and flood irrigation are strictly prohibited. Preventing water droplets from splashing during watering is an important measure to prevent this disease.

Control Methods for Corn Bacterial Wilt

Corn bacterial wilt, also called corn stalk rot, is an important soil-borne fungal disease that harms corn roots and stem bases. The incidence rate in our province is generally 10-20%, and in severe cases reaches more than 30%. Once bacterial wilt occurs, the entire plant quickly dies, generally in only 5-8 days, and in fast cases in only 2-3 days.

1. Select disease-resistant varieties

Planting disease-resistant varieties is the most economical and effective control measure. Corn varieties bred in recent years such as Ludan 50, Ludan 981, Nongda 3138, and Yuyu No. 22 are both high-yielding and disease-resistant, and can be promoted for planting in production.

2. Rotation and crop replacement

Continuous planting of corn in the same plot for years can cause large accumulation of pathogens in the soil, and the disease will worsen year by year. If rotated with non-host crops such as soybean and peanut, the occurrence of the disease can be significantly reduced.

3. Use coated seeds

Seed coating agents contain fungicidal ingredients and trace elements, which can both resist pathogen infection and promote seedling growth and enhance disease resistance. The amount of seed coating agent used is 1/40-1/50 of the seed amount. Apply zinc and potassium fertilizers. The pathogen of corn bacterial wilt is a weak parasite, and it causes massive disease only when corn growth weakens in the middle and late stages. Applying zinc and potassium fertilizers can make corn grow robustly, greatly improve corn disease resistance, and reduce the incidence rate. The method is: at the corn seedling stage, use 1.5-2 kg of zinc fertilizer and 10-15 kg of potassium fertilizer per 1/15 hectare, mix them and apply in holes at 7-10 cm from the corn stem base. Pour medicated water. When sporadic diseased plants are found in the middle and late stages of corn growth, use metalaxyl at 400 times dilution or carbendazim at 500 times dilution to irrigate the roots, pouring 500 ml of medicated liquid per plant, which has a good therapeutic effect.