The Latest Control Methods for Peanut Southern Blight
Peanut southern blight is one of the major diseases harming peanuts. After the roots, pods, and stem bases of peanuts are infected, they initially appear brown and soft-rotted. White silky mycelium appears at the root-stem area above ground, and white silky threads often first form at the stem base near the ground and on the nearby soil surface. The diseased area gradually turns dark brown and glossy. Now let us take a look at the control methods for peanut southern blight!
Symptoms of Peanut Southern Blight Damage
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 affected stem base is covered by long spindle-shaped lesions with a light brown to red, corky, raised appearance. Under drought conditions, lesions on the stems occur below the soil surface, appear brown and spindle-shaped, about 0.5 cm long, and contain rapeseed-like sclerotia. The stems and leaves turn yellow and gradually die, and the peanut pods rot.
Conditions for the Onset of Peanut Southern Blight
The pathogen overwinters as sclerotia or mycelium in the soil or on diseased residues 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 they almost do not germinate at 7 cm in the soil. The following year, the sclerotia germinate and produce mycelium, which invades through the epidermis or wounds at the root-stem base of the plant. It can also invade the gynophore or pods, and seeds can also carry the pathogen. In the field, the pathogen spreads through flowing 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 clears up immediately after rain, diseased plants rapidly wither and die. Continuous cropping and early sowing result in more severe disease.
Control Methods for Peanut Southern Blight
1. After harvest, promptly remove diseased residues and deep plow. Rotate with gramineous crops such as rice, wheat, and corn for more than 3 years. It is recommended to apply compost fermented with effective microorganisms or fully decomposed organic fertilizer to improve soil aeration.
2. 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 dress them with 50% carbendazim wettable powder at 0.5% of the seed weight. After the disease occurs, mix 1 kg of 50% seed-dressing dual powder 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. In the early stage of the 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, applying 100-200 ml of the prepared solution per plant.