How to control peanut southern blight? A detailed guide to practical techniques
Peanut southern blight is one of the major diseases harming peanuts. Its symptoms are that after the peanut roots, pods and stem base are damaged, they first appear as brown soft rot, and white silky mycelium appears at the root crown area above ground. Below is a look at a detailed guide to the control techniques for peanut southern blight!
1. Conditions for the occurrence of peanut southern blight
The pathogen overwinters in the soil or on diseased residues as sclerotia or mycelium and can survive for 5-6 years. Most are distributed in the 1-2 cm surface soil layer. The germination rate of sclerotia below 2.5 cm is significantly reduced, and at 7 cm in the soil they almost do not germinate. The following year the sclerotia germinate and produce mycelium, which invades through the epidermis or wounds at the base of the plant stem, and can also invade the ovary stalk or pods. Seeds can also carry the pathogen. In the field, the pathogen spreads through running water or insects. High temperature, high humidity, heavy clay soil, poor drainage, low-lying land and rainy years make the disease more likely to occur. If it turns sunny immediately after rain, diseased plants quickly wither and die. Continuous cropping and early sowing result in more severe disease.
2. Damage symptoms of peanut southern blight
Under high humidity conditions, the above-ground part of infected plants can be covered by white mycelial strands, which then spread to the nearby soil surface and infect other plants. In extremely humid environments, the mycelial clusters are not obvious, while the damaged stem base is covered by long spindle-shaped lesions with light brown to red corky raised areas. Under dry conditions, the lesions on the stems occur below the ground surface, are brown and spindle-shaped, about 0.5 cm long, and have rapeseed-like sclerotia. The stems and leaves turn yellow and gradually die, and the peanut pods rot.
3. Control methods for peanut southern blight
1. Improve soil conditions
After harvest, promptly remove diseased residues and deep plow, and carry out rotation with gramineous crops such as rice, wheat and corn for more than 3 years. The use of compost fermented with effective microorganisms or thoroughly decomposed organic fertilizer is recommended to improve soil aeration.
2. Select seeds with strong disease resistance
Sow spring peanuts appropriately late, and clear the seedlings and practice seedling hardening during the seedling stage to improve disease resistance. At the same time, select disease-free seeds and treat them with 50% carbendazim wettable powder at 0.5% of the seed weight. After the disease occurs, use 1 kg of 50% seed-dressing dual powder mixed with 15 kg of fine dry soil to make medicated soil to cover the diseased holes, using 75 g of medicated soil per hole.
3. Chemical control
At the early stage of disease, spray or drench with Fengqia Genbao at 600-800 times dilution, or 50% benomyl wettable powder, or 50% iprodione wettable powder, or 50% procymidone (Sumilex) wettable powder, or 20% tolclofos-methyl emulsifiable concentrate at 1000-1500 times dilution, spraying 100-200 milliliters of the prepared solution per plant.
The above is the introduction by Tuliu.com to the control methods for peanut southern blight. Peanut southern blight begins to become active under high temperature and high humidity conditions and infects peanuts. Sandy soil, continuous cropping, excessive planting density and rainy days result in more severe disease.