Harmful symptoms and Control methods of White Silk Disease of Peanut

Peanut white silk disease is one of the main diseases harmful to peanuts. Peanut roots, pods and stem bases show brown soft rot at the beginning, and there are white silk hyphae in the aboveground rhizomes. White silk filaments are often formed at the base of the stem near the ground and on the soil surface near it, and the disease parts gradually become dark brown and shiny. Let's take a look at the prevention and control methods of peanut white silk disease.

Harmful symptoms of white silk disease of peanut

Under high humidity conditions, the aboveground parts of infected plants can be covered by white mycelium bundles, and then spread to the nearby soil surface and spread to other plants. In extremely humid environment, the mycelium cluster is not obvious, but the base of the damaged stem is covered by long fusiform disease spot with light brown or even red cork bulge. Under drought conditions, the disease marks on the stem occurred under the ground surface, showing brown fusiform, about 0.5 cm long, with rape seed sclerotia, stems and leaves turned yellow, gradually withered, and peanut pods rotted.

Incidence conditions of White Silk Disease of Peanut

The pathogen overwinters with sclerotia or hyphae in the soil or on the diseased remains, and can survive for 5 ~ 6 years, most of which are distributed in the surface soil layer of 1 cm to 2 cm. The germination rate of sclerotia below 2.5 cm decreased obviously, and there was almost no germination at 7 cm in the soil. The sclerotia germinated the following year and produced hyphae, which invaded from the epidermis or wound at the base of the plant rhizome, and could also invade the ovary stalk or pod, and the seeds could also carry bacteria. Germs spread in the fields by running water or insects, high temperature, high humidity, soil viscosity, poor drainage, low-lying land and rainy years are easy to occur, clear up immediately after rain, diseased plants wither and die quickly, and the disease is serious in continuous cropping land and sowing early.

Control methods of White Silk Disease of Peanut

The main results are as follows: 1. Remove the disease and residue in time after harvest, turn deeply, rotate with rice, wheat, corn and other gramineous crops for more than 3 years, and advocate the application of compost or mature organic fertilizer made by enzyme bacteria to improve soil permeability.

2. Spring peanut should be sowed late, and the seedlings should be squatted at seedling stage to improve disease resistance. At the same time, the disease-free seeds were selected, and the seeds were mixed with 50% carbendazim wettable powder with 0.5% seed weight. After the disease, the disease was covered with 50% seed double powder 1 kg of fine dry soil and 15 kg of fine dry soil, and 75 grams of soil was used for each hole.

3. Spray Fengqian Genbao 600-800 times or 50% carbendazim wettable powder or 50% propofol wettable powder or 50% carbendazim (Sukeling) wettable powder at the initial stage of the disease, 20% methyl ibuprofen EC 1000 × 1500 times, each plant sprayed 100 ml of the right solution.

Harmful symptoms and control methods of plant white silk disease (picture)

White silk disease, also known as sclerotial root rot and sclerotial seedling blight, harms the roots and stems of seedlings and young trees, mainly harms Camellia oleifera, paulownia, catalpa, citrus, apple, sycamore, paulownia, walnut, Masson pine and other tree species, and can also cause peanuts, green onions and many other crops, mainly distributed in the south and southwest of Henan Province. Let's take a look at the prevention and control techniques of white silk disease.

Symptoms of white silk disease

White silk disease usually occurs in the root stem or the base of the stem of the seedling, and the cortex of the susceptible root stem gradually turns brown necrotic, with severe cortical decay. After the seedlings were damaged, it affected the absorption of water and nutrients, resulting in poor growth, the aboveground leaves became smaller and yellowed, the internodes of the branches were shortened, and the branches and leaves withered seriously, and the whole plant withered after one week of the disease spot. Under wet conditions, the damaged rhizome surface or near-ground soil surface was covered with white silk mycelium. In the later stage, many rapeseed-like small sclerotia were formed in the mycelium, which were white at first, then gradually changed from yellowish to yellowish brown, and then became tea-brown. The hyphae gradually extend downward to the roots, causing root rot. The leaves of some tree species are also susceptible to disease, with brown ring-shaped disease spots and small sclerotia growing on the diseased leaves.

The pathogen of white silk disease

The asexual generation of the pathogen causing white silk disease of trees is Sclerotinia uniformis. The optimum temperature for the development of Alternaria alternata was 30 ℃, the highest was about 40 ℃, and the lowest was 10 ℃. It could grow at pH 1.9 to 8.4. PH5.9 was the most suitable for reproduction, and light could promote sclerotia production. Sclerotia will germinate under suitable conditions, no dormancy period, can dormancy under bad conditions, sclerotia can survive in soil for 5-6 years, and survive longer under low temperature and dry conditions.

Prevention and treatment of White Silk Disease

1. Nursery site selection: nursery land should be selected with fertile soil, loose soil and good drainage. The nursery with serious disease of the previous crop should be rotated with Gramineae crops for more than 4 years before it can be replanted.

2. Deep ploughing in winter: in the susceptible nursery, deep ploughing should be carried out every winter to bury the remains of diseased plants in the soil to remove the source of infection.

3. Soil disinfection: before raising seedlings or afforestation, 1000 grams of pentachloronitrobenzene wettable powder per mu and 20 kilograms of fine soil should be mixed and scattered evenly in the sowing ditch or around the tree holes. For lightly susceptible seedlings, you can dig up the soil at the rhizome, dry the rhizome for several days or spread quicklime to disinfect the soil.

4. strengthen management: timely fertilization, watering, drainage and weeding should be carried out during the seedling growing period, so as to promote the vigorous growth of seedlings and improve the disease resistance of seedlings. In summer, it is necessary to protect against sun exposure, reduce the harm of burns, and reduce the chances of bacterial infection.

5. Chemical control: at the initial stage of the disease, Fengqian Genbao can be used 600 times or 800 times or 1% copper sulfate solution can be used to irrigate the roots of diseased plants, or 50 grams of 25% verapamil wettable powder and 50 kg of water can be used to irrigate the roots of diseased plants, or 50 ml of 20% methyl parathion EC can be used per mu, 50 kg of water can be added, and sprayed every 10 days or so.

How to control white silk disease of peanut

Peanut white silk disease does great harm to peanut plants and pods, and serious cases will even cause plant death, making farmers must have a headache, so how to control the effect is good, let's take a look.

Control methods of White Silk Disease of Peanut

(1) to deeply turn over and improve the soil and strengthen field management. Remove the diseased body before the peanut is harvested. Ploughing the soil deeply after harvest can reduce the source of overwintering bacteria in the field. Achieve the matching of "three ditches" after peanut sowing, and drain the stagnant water from the field in time after rain.

(2) Chemical prevention and control. Spray 20% triadimefon EC 1000 times in the early podding stage of peanuts, or 1000 times of prohydantoin for control. It can also be irrigated with triadimefon, triadimefon, carbendazim and other agents during the disease period, and the control effect is very obvious.