How to prevent and control cotton blight? Cotton blight is extremely harmful, how to prevent and con

After the occurrence of cotton blight, it often leads to the death of cotton seedlings in patches, and the pathogen overwinters on cottonseed linters with conidia, and a few overwinters with mycelium latent in the seed coat of cotton seeds or in the cotyledons, and the seed carrier is an important source of primary infection. Therefore, comprehensive control measures should be adopted for the prevention and control of cotton seedling diseases, mainly agricultural control, supplemented by cotton seed treatment and timely spraying control.

Cotton seeds are infected before germination and cause rot seeds, and after germination, they are infected before they are unearthed and cause rot buds. After the cotton seedlings are unearthed, they are damaged in the early stage of the base near the soil surface, and the lesions gradually expand and surround the whole base and shrink obviously, and the seedlings wilt and lodging and die. When the diseased seedlings are pulled up, the cortex below the base of the stem is left in the soil, and only the sharp sage-like xylem remains.

After the cotyledons are damaged, yellow-brown irregularly shaped lesions are mostly produced in the middle of the cotyledons, which often fall off and perforate. The disease often causes the death of cotton seedlings in patches. White sparse mycelium is common in the stem base and around the stem of diseased and dead seedlings, and on the soil surface.

There are many types of seedling diseases, which often occur in mixture, so the comprehensive control measures for the prevention and control of cotton seedling diseases should be mainly based on agricultural control, supplemented by cotton seed treatment and timely spraying control.

Before sowing, high-quality cotton seeds must be selected, depiled by sulfuric acid, in order to eliminate various pathogens on the surface, eliminate small seeds, deflated grains, miscellaneous seeds and insect-eaten seeds, and then dry seeds for 30-60 hours to improve the germination rate and germination potential of seeds, and enhance the disease resistance of cotton seedlings.

Control measures: 1) Reasonable crop rotation, deep ploughing and soil modification 2 Reasonable crop rotation can reduce the accumulation of pathogenic bacteria in the soil and reduce the incidence of disease.

2) Sowing and transplanting seedlings at the appropriate time; On the premise of not missing the agricultural time, sowing seeds at the right time can reduce the disease.

3) Sufficient basal fertilizer and reasonable top dressing: Increasing organic fertilizer in cotton fields can promote the growth of cotton seedlings, improve disease resistance, and inhibit pathogenic bacteria from infecting cotton seedlings.

4) Strengthen field management: after the emergence of seedlings should be early tillage, generally in the emergence of about 70 to carry out tillage loosening soil, in order to improve soil temperature, reduce soil moisture, make the soil loose, good aeration, conducive to the development of cotton seedling roots, inhibit the root disease. When there are many rainy days, ditch drainage in time to prevent stains.

Strengthen insect control, and time seedlings, and burn diseased seedlings and dead seedlings in a centralized manner to reduce the infection of field pathogens.

Cotton blight is caused by S. solidus. Blight is mainly parasitic and can also be saprophytic. The pathogen overwinters in the soil or on diseased residues in the form of mycelium or sclerotia, and the sclerotia formed in the soil can survive for several months to several years.

S. solizum can resist adverse environmental conditions such as high temperature, freezing, and drought, and is very adaptable, generally able to survive for several years, and is resistant to acid and alkali, and can grow in the range of pH value 2 4 9 2. Therefore, the host range of the bacterium is extremely wide and widely distributed.

1.Field performance. Before the cottonseed was unearthed, the stems near the soil surface showed yellow-brown lesions, and after being infestation, irregular yellow-brown lesions also appeared, and the whole plant showed shrinkage, and the cotton seedlings withered.

The primary infection of blight mainly comes from soil, and infected seeds can also be transmitted. Before the cotton seedlings are unearthed, S. solidis can infect young roots and young shoots, resulting in rotten seeds and buds. Cotton seedlings are the most susceptible to disease at the cotyledon stage, and if the soil temperature continues to be about 15 degrees Celsius within one month of the cotton seedlings being unearthed, or even encountering cold snaps or low temperatures and rain, the blight will occur seriously, resulting in a large number of dead seedlings.

If the temperature is low and rainy before harvesting, the cotton boll will be damaged, and the fungus can also invade the inside of the human seed, becoming the first infection of the next year**. Sowing too early, low temperature, slow germination of cotton, long bacterial infection, severe disease. The continuous cropping of cotton fields for many years is seriously ill.

Cotton fields with low-lying terrain, poor drainage and heavy soil are more severely affected.

2.Prevention and control methods. Reasonable crop rotation, rotation with gramineous crops for 3 to 5 years, cut off the source of bacteria in the soil.

Deep ploughing and ploughing the ground, turning the dead branches and leaves in the cotton field into the lower layer of the soil together with the bacteria and pests, has a certain effect on the prevention and control of diseases at the seedling stage. If there is a drought in spring, spring irrigation can also be carried out early, because irrigation before sowing will reduce the ground temperature, which is not conducive to the growth of cotton seedlings. Reasonable fertilization, increase the application of well-rotted organic fertilizer or bio-organic moon bar.

Timely sowing, spring cotton is generally 5 cm deep, soil temperature above 15 degrees Celsius for the suitable sowing date, strengthen seedling management. Morning seedlings, early tillage, improve the temperature of the soil, cultivate strong seedlings.

Attention should be paid to the use of pesticides in the prevention and control of pesticides. Select seeds and dry them half a month before sowing. With 50 carbendazim wettable powder with 0 5 cottonseed weight, or 40 pentachloronitrobenzene plus 50 carbendazim with 0 5 cottonseed weight, anthracnose and red rot can be used to treat both anthracnose and red rot.

After the emergence of seedlings, if there is a possibility of outbreak of seedling disease in low temperature and rainy weather, 50 methyl tobuzin or 50 carbendazim wettable powder 600 times liquid, 70 chlorothalonil wettable powder 600 800 times liquid spray, or 800 1000 times liquid liquid with Likujing root irrigation or spraying.

This disease is not easy to prevent and control, and it is difficult to prevent and control it with pesticides alone, and it must be combined with agricultural measures.

Improve sowing quality: should choose good maturity, full grains, high purity of excellent disease-resistant varieties, strong viability, after sowing seedlings to speed up, neat and strong, not easy to be infected by pathogens, so the disease is light (the germination rate of seeds should be more than 80%). When the ground temperature of 5 cm is stable at 14, grasp the cold tail and warm the head to sow seeds.

Some pesticides should be sprayed, and some pesticides can prevent and control cotton blight.

Pesticides should be sprayed in a timely manner, and water and fertilizer should be well managed, and sufficient sunlight should also be maintained.

Cotton blight is commonly known as root rot and black root disease. Caused by Rhizoctonia blight, it is mainly parasitic and can also decay. Pathogens overwinter in the soil or on diseased organisms with mycelium or sclerotia.

The sclerotia that form in the soil can live for months to years. Sclerotinia solidum can resist adverse environmental conditions such as high temperature, freezing, drought, etc., has strong adaptability, can generally survive for several years, is resistant to acid and alkali, and can grow in the pH range. As a result, the bacterium has an extremely wide range of hosts.

When the cottonseed seedlings are injured, yellow-brown spots appear at the base of the stem near the ground, which gradually expand and concave inward. As a result of excessive water loss, the depression shrinks and thins, then turns blackish-brown and decays. Cotton seedlings wilt after being invaded.

The first infestation of blight mainly comes from the soil, but also from seeds with bacteria. Before cotton seedlings emerge, Rhizoctonia sylvestii infects young roots and shoots, causing seeds and shoots to rot. Cotton seedlings are most sensitive to diseases at the cotyledon stage.

If the soil temperature of cotton seedlings continues to be about 15 within a month after unearthing, or even if they encounter cold snaps or low temperatures and rain, bacterial wilt will seriously occur, causing a large number of seedlings to die. If the weather is cold and rainy before harvesting, the bolls will be damaged and bacteria will invade the seeds, becoming the first source of infection next year. Cotton seedlings are sown early, low temperature, slow germination, long infection time, and severe disease.

For many years, the continuous cropping cotton field has serious diseases. Cotton fields with low-lying terrain, poor drainage and high soil viscosity are more severely affected.

Prevention methods: 1. In the early stage of spraying, collect a bucket of water with 10ml + 5ml of water, and then spray the main stem of cotton seedlings to make the liquid drip into the soil along the main stem, 2 3 times is appropriate. The interval is 10-15 days.

It has a special effect on preventing cotton seedlings from wilting.

2. Root irrigation. At the beginning of the disease, 15ml of ginseng purfumycin and 25ml of Tianda 2116 Zhuangmiaoling were used to irrigate the roots 2 3 times, with an interval of 5 7 days.

3. You can also use silex (shimaidan) 10ml + 5ml Aidoshou or Shenzimycin 15ml + Tianda 2116 Zhuang Miaoling 25ml to add water, peel off the soil around the cotton tree, expose the lesions, and brush 2 3 times in a row with a brush, with an interval of 7 10 days.

When planting cotton, you can sprinkle some pesticides and spray some pesticides, so that you can prevent this disease of cotton.

To ensure soil fertility, we must do a good job of prevention, use pesticides and fertilizers in a timely manner, do a good job of loosening the soil, and also kill insects in time.

To do a good job of prevention, to water in time, to prune branches and leaves regularly, but also to use pesticides and fertilizers, to choose different effects according to different situations, to prescribe the right medicine.

Prevention and control methods: 1. Select disease-resistant varieties. Crop rotation with other grasses and rice crop rotation is better.

In winter, remove the cotton firewood, weeds and the remaining cotton residues and leaves on the ground in time to prevent the spread of germs. Deep ploughing of the land in autumn, timely cultivation and loosening of the soil, maintain the permeability of the soil, and reduce soil moisture. Increase the application of phosphorus and potassium fertilizers.

At the same time, foliar fertilizer is sprayed according to the growth of cotton. Reasonable dense planting, timely removal of diseased and disabled bodies. 2. Carefully quarantine and protect disease-free areas.

There is no disease in China's 2 3 or so cotton areas, so it is necessary to do everything possible to protect the disease-free areas. Cotton seeds in disease-free areas must not be imported from the diseased areas, and it is strictly forbidden to use unhot-pressed cotton cakes in the diseased areas to prevent the introduction of wilt and verticillium wilt. Promote the use of compost made by enzymes and bacteria or decomposed organic fertilizer.

3. The use of Bacillus subtilis or bacterial fertilizer has a certain control effect in recent years, and it is necessary to test the adaptability of the strain locally, otherwise the strain will be difficult to survive and the control effect will be poor. To promote bacterial fertilizer, there must be a process of introduction, testing, demonstration and promotion.

In the process of cotton production, it is difficult to occur cotton blight, which is a devastating disease that prevents cotton production, so it is called cotton"Cancer"The disease is caused by Fusarium wilt infection, which occurs in all major cotton growing regions of the world, and was discovered in Alabama as early as 1892 and spread to other parts of the United States and around the world over time.

<> 1934, cotton blight in Nantong, Jiangsu Province occurred for the first time in China, and then began to spread and develop in China, in the early 50s of the 20th century, cotton blight occurred only in Shaanxi, Shanxi, Jiangsu and other provinces in China, but with the passage of time. The spread of the disease is more serious, the disease has occurred in various cotton planting areas, and in the 70s of the 20th century, the disease has caused serious harm in Shaanxi, Sichuan, Jiangsu, Yunnan, Shanxi, Henan and other provinces, causing serious losses to local cotton production. Let's take a look at the symptoms, occurrence rules and control methods of Fusarium wilt in cotton.

Methods of prevention and control. protection of disease-free fields; Due to the rapid spread of the disease, in order to prevent pathogens from entering disease-free fields, the quarantine system is strictly implemented, the seeds are prohibited from spreading in diseased areas, the seed supply base is established and left the field, and the disease-free and improved varieties are cultivated on the spot to eliminate the disease spots in time; Strengthen the management of cotton fields, find sporadic diseased plants in a timely manner, and destroy them in a centralized manner; The cottonseed in the diseased field should be treated at high temperature and should not be reserved for planting. After the cotton is harvested, it is necessary to clean up the cotton fields in a timely manner, burn the dead branches and fallen leaves of the Jiangmingzhu in a concentrated manner, and strive to eliminate the wheat crops that have been damaged in the cotton fields for a long time. Soil grouting and disinfection can be carried out to prevent the occurrence of Fusarium wilt, and the commonly used agents are as follows.

Methyl bromide; The soil of the affected cotton field was loosened, leveled and covered with plastic film, steamed with 20 kg of methyl bromide fumigated plum pants per mu for 15 days, and then uncovered the plastic film for 7 days, so as to effectively control Fusarrine and other harmful organisms in the soil; Open 25 holes per square meter in the affected cotton field, the spacing is 20cm, the hole depth is about 15cm, each hole is filled with 5ml, it is necessary to cover the soil for 10 days, turn over the soil and prepare the land, so that the residual gas volatilizes, the use of the method is more thorough, but the drug contains highly toxic, and the use should be used in strict accordance with the operating procedures, and the cost is higher than that of the car beam.

Be sure to protect the disease-free area, cut off all the plants in some diseased areas, isolate them, and then tell Liang to choose phosphate fertilizer and potassium fertilizer, so that you can improve the high disease resistance of Tanyun, and then you can also choose aseptic net fertilizer, to cultivate and weed, usually you can also loosen the soil in time, drink pesticides to remove pests, the humidity is not too large, and regularly clean up the dead branches and leaves.

Select varieties with excellent varieties, strict quarantine, remove diseased roots in time when disease occurs, carry out high-temperature treatment, timely spraying of pesticides, and soil disinfection.

Proper fertilization. Proper fertilization during the growth period of cotton can give cotton enough nutrients and enhance the immunity of cotton.

Answer]: 1. Symptoms.

1) Cotyledons and true leaves are infected with purple-red margins at the beginning and gray-white small round spots in the middle, and the posterior lesions expand or merge into irregularly shaped lesions. Some lesions** appear concentric wheel lines, on which small black particles are scattered, that is, the conidia of pathogenic bacteria. The diseased part is often broken and scattered, when the humidity is high, the young leaves appear water-soaked lesions, and then expand rapidly like boiling water, then they have been scalded, wilted and blackened, and seriously dried up and fell off, turning into bare stalks and dying.

2) The petiole and stem are infected and the lesions are light brown, purple-red, slightly concave, scattered with small black spots on the surface, and the severe stems and branches are withered or dead.

3) The lesions of cotton boll infection are similar to those on the stem. The middle color is darker, black. When the humidity is high, the disease spreads rapidly, causing the cotton boll to become a stiff valve, and the boll is incomplete or not cracked.

2. Prevention and control methods.

crop rotation and stubble; Deep ploughing, deep ploughing, reasonable dense planting, improve ventilation and light transmission conditions.

2) After cottonseed sulfuric acid delinting, mix vebodan and carbendazim 1: seed coating agent, which can not only prevent diseases but also treat aphids. The onset of disease at the seedling stage or adult plant stage can be sprayed with 800 times of 65% dysen zinc or 1000 times of 70% methyl tobuzin.