Chinese cabbage has downy mildew, how to prevent and control it to improve yield?

Downy mildew is one of the three key diseases of Chinese cabbage (downy mildew, virus disease, soft rot), which mostly occurs in the middle and late stages of Chinese cabbage growth and development, the key is because of low temperature, soil moisture content is too large and caused by fungal degeneration.

Downy mildew pathogens in cabbage fields are mainly spread through cyclones, germinating and invading the body of cabbage under the condition of water droplets or shrinking water on the leaves, rainy and humid environment, beneficial to the germination and invasion of pathogens, when the temperature is low, precipitation or dense fog, the disease will spread rapidly, at the same time, the terrain is low-lying, the planting is too dense, the natural ventilation and light transmittance are not good, and the plant lacks vitamin A, which will also induce downy mildew. The comprehensive control of agriculture, animal husbandry and chemical fertilizer can reduce the occurrence of downy mildew, reduce the disease, promote the physical and mental health of cabbage growth and development, and improve the production and quality of cabbage.

First of all, a small number of diseased plants were found, and they were immediately pulled out, buried outside the field, and the soil layer of the diseased plants was disinfected and sterilized to prevent the spread of germs and infection. Increase fertilization and replace the sprayed potassium dihydrogen phosphate to promote the growth and development of cabbage, improve plant disease resistance, and reduce the occurrence of downy mildew, so as to improve efficiency and promote quality. Improve the cultivated loose soil, improve the soil permeability, remove the water immediately on rainy days, reduce the soil moisture content, and reduce downy mildew.

For chemical fertilizer prevention, you can use 75% mancozeb 600 times solution, or 58% methalen manganese zinc 800 times solution, or 64% disinfectant alum 400 times solution, or 72% downy mildew cyanide mancozeb 600 times liquid sprayer, which can have a good prevention and control effect on cabbage downy mildew.

If the residue of the fungus is stored in the soil to survive the winter, or the trouble is big on the attached seeds, next year's planting is still like this, because the seed soil layer is stained with the fungus, climate change has a great impact on the downy mildew of Chinese cabbage, and the environmental humidity above 70 is beneficial to the prevalence of cabbage, when the temperature is 24 degrees, it is easier to get sick, and the best temperature is about 12 degrees. After squatting seedlings, improve fertilizer and water management, immediately feed organic fertilizer, use phosphorus and potassium fertilizer as auxiliary fertilizer, and pay attention to the use of leaf fertilizer in the middle and late stages to avoid senescence, which can improve the disease resistance of Chinese cabbage, and can also be planted in ridge forming and non-cruciferous vegetable rotation.

When planting, disease-resistant varieties should be selected, crop rotation should be implemented, planting methods should be reformed, and the countryside should be cleaned.

Selection of disease-resistant varieties: In the actual planting, the disease-resistant varieties such as summer holly series, heat-resistant white series, green shame series and green hemp leaf strains are promoted, and the downy mildew resistance is strong. Implement crop rotation:

Reasonable rotation with non-cruciferous crops for 2-3 years can be considered, preferably water-drought rotation, because the flooded conditions are not conducive to the survival of pathogenic bacteria, which can significantly reduce the number of pathogens in the soil.

It is necessary to strengthen the management of water and fertilizer, do a good job in fertilization and top dressing, watering should be irrigated with small water, and drainage should be carried out in time after rain. Combined with pest control, foliar fertilizer is sprayed, which can improve the disease resistance of plants.

There were oranges in all growth stages, mainly to the leaves. When the cotyledons are diseased, there is a white clear layer on the back of the leaves, and there are no obvious symptoms on the front of the true leaves of the seedlings, and the seedlings die in severe cases. At the adult stage, the front of the leaf appears grayish-white, pale yellow or yellow-green with inconspicuous edges, and then expands into yellow-round brown lesions, which are polygonal or irregular due to the restriction of leaf veins, and the back of the leaf is densely covered with white layers.

When there are many diseased spots, they are connected to each other, so that the diseased leaves die locally or the whole leaf.

Peronospora is a fungus of the subphylum Flagellates. The oospores are more and more mole in the diseased tissue, in the soil, or attached to the seeds, or the mycelium is used to grow on the remaining seed plants. The sporangia germinate in the next spring from oospores or dormant hyphae.

After the spring vegetables are harvested, the pathogens invade the autumn vegetables after two months of dormancy in the field with oospores. The appropriate temperature for the occurrence of the disease is 16-20, and the relative humidity is about 70. After the Chinese cabbage enters the rosette stage, with the rapid growth of the plant, the outer leaves begin to senesce, if the temperature is high, or there is more rain, the light is insufficient, the fog is more, the dew is heavy, and the disease occurs more severely.

In production, early sowing, excessive density, poor permeability in the field, wild growth of plants or severe lack of fertilizer during the growing period will aggravate the disease.

Sowing at the right time, appropriate sparse planting; Apply plantar fertilizer, increase phosphorus and potassium fertilizer. Morning seedlings, late seedlings, moderate squatting seedlings. Frequent irrigation of small water, timely drainage after rain.

Remove diseased seedlings, remove diseased residues in the field in time after harvesting, and take them out of the field to be buried or burned. When there is more disease in the field, the dose should be increased to strengthen the prevention and control, and when the disease is more common, the following fungicides or formulas can be used for prevention and control: 800-1200 times of frost carb hydrochloride-flupyramide suspension; 1000 times of frost carb-ethphosphonate soluble water solution l0 cyanofrostazole suspension 2500 times liquid; 35 1000-1500 times of enoyl-Fumei double wettable powder; 70 furoyl-manganese-zinc wettable powder 600-1000 times; 440g l diyne-chlorothalonil suspension 600-1000 times; Spray water evenly, and spray once every 7-10 days depending on the condition.

First of all, you can choose disease-resistant varieties, such as the state of the sparrow said green sunflower series, heat-resistant white series, etc., but also pay attention to the reincarnation of crops, the time in 2 3 years, the best is the reincarnation of water and drought, the planting method is reformed, the use of narrow planting and wide planting method planting, often clean the garden, the Chinese cabbage sail early spray of the drug should also control a certain amount of the family system.

The seeds can be disinfected before the Chinese cabbage is sown, and the liquid can be balanced fertilization to improve the disease resistance of the Chinese cabbage.

Choose disease-resistant varieties, implement crop rotation, reform planting methods, use wide and narrow rows to plant, regularly pull out diseased seedlings, and use some pesticides.

During the planting process, it is necessary to water and fertilize it, and also to apply some insect repellent to increase the yield.

When the disease occurs in the cotyledon stage, a white mold layer appears on the back of the leaf. Under high temperature conditions, nearly round blight spots often appear on the affected area. In severe cases, white mold also appears on the stems and petioles, and the seedlings and leaves die.

At the adult stage, small spots from pale green to pale yellow appear on the front of the leaves, which are yellowish-brown after enlargement. The spots are confined by veins and are polygonal in shape. When wet, a white mold layer appears on the spots on the back of the leaves; When Chinese cabbage enters the endocardial stage, when the conditions are suitable, the lesions on the leaves increase and are parallel, the leaves are yellow, and the diseased leaves develop from the outer leaves to the inner leaves.

In severe cases, the plant can not endocardium.

The optimal temperature for sporangia production was 8 12, the optimal temperature for sporangia germination was 7 13, the maximum temperature was 25, and the minimum temperature was 3. The sporangia can germinate in water droplets at a suitable temperature of 3 to 4 hours, and the optimal invasion temperature is 16. The optimal temperature for mycelial growth and development is 20 24, the optimal temperature for oospore production is 10 15, and the relative humidity is 70% 75%.

Pathogens overwinter in the soil or in cruciferous vegetables or in the roots of winter storage plants, and sometimes they can be mixed into seeds in summer or winter.

In order to prevent and control downy mildew of Chinese cabbage, soak seeds in warm water for 2 hours, soak seeds in downy mildew hydrochloride solution 500 times, 1 hour each time, or mix seeds with 53% methalene-manganese-zinc water-dispersible granules, Luo Junjingjiashuang suspension seed coating and 25% methalen wettable powder according to the weight of seeds. It can worsen the condition. As in Hebei, we can choose the planting time according to the local environment of the field preparation and rental room, and the planting spacing should not be too close.

It is necessary to fertilize the soles of the feet, increase the amount of phosphorus and potassium fertilizer, remove the sick and disabled corpses in the field, take them out of the field more than 100 meters, and bury them deep or burn.

Field surveys should begin at the Chinese cabbage seedling stage. After the central diseased plant is found, it should be immediately pulled out and sprayed for control, and thoroughly controlled at the end of the rosette. In order to facilitate the later prevention and control, it is convenient for prevention and control operations.

The agent can be 200-300 times that of 40% aluminum phosphate wettable powder, 500 times that of 70% aluminum manganese-zinc phosphate wettable powder, 600 times that of 70% chlorothalonil wettable powder or 800-1000 times that of 72% frost urea cyanide manganese zinc wettable powder, and 100 million live spores per 267 grams of square meters can prevent downy mildew of Chinese cabbage by strengthening fertilizer and water management, spraying methafen, manganese zinc, frost urea cyanide and other chemical agents. Pay attention to water and fertilizer management, and spray pesticides in time for prevention. Thiamine can be used to control downy mildew in Chinese cabbage.

Downy mildew can be controlled by downy mildew and enoylmorpholine.

You should choose a good fertilizer for wild age, Kai Rush and should also spray some pesticides to prevent insect pests, and should also be watered by Sun Sheng, weeding frequently, etc., so that you can carry out good control.

The appropriate sowing date should be determined according to the stubble, variety and climate. The disease of early sowing is severe, and the disease of late sowing is mild, but insufficient. However, in high temperature and drought years, Chinese cabbage should be sown late, and the disease resistance of the mixed varieties is stronger than that of the farmer's varieties, so the sowing date can be arranged in advance.

1. Choose disease-resistant varieties; 2. For sowing at the appropriate time, the appropriate sowing date should be determined according to the stubble, variety of wild celery and climate; 3. To treat insects and prevent viral diseases, the early virus strains are often the early occurrence and recurrence of downy mildew. Chinese cabbage virus disease is transmitted by aphids, and early prevention and control of aphids should be done, and the applicable drugs are 5% acetamiprid emulsifiable concentrate, cyhalothrin wettable powder and deltamethrin emulsifiable concentrate, etc., and the virus strains are found to be removed in time; 4. Pull out the central diseased plants and clean up the diseased leaves; 6. For the prevention and treatment of Songbi drugs, it is necessary to choose the corresponding prevention and control agents according to the onset period.

Downy mildew is one of the most widespread and harmful diseases of cabbage vegetables.

Symptoms and their identification: Downy mildew can infect and harm Chinese cabbage at all growth stages. Xiao Miao was killed:

In the early stage, a white mold layer is produced on the back of the leaf, and there are no obvious symptoms on the front of the leaf, and the stem and leaf are yellow and dead in severe cases. Adult plant damage: white mold appears on the back of the leaf, pale green lesions appear on the front of the leaf, and gradually turn yellow or yellow-brown, and finally dry up.

Since the expansion of the lesion is limited by the leaf veins, the lesions are formed in the mesophyll between the leaf veins, which are polygonal. After the heart-to-heart period of Chinese cabbage, the disease develops rapidly, and a large number of dead spots are connected into patches, and the bulbs are damaged in severe cases, which affects the quality of products.

Prevention and control methods: choose disease-resistant varieties. Seed sterilization.

In order to prevent seeds from carrying bacteria, 50% Fumei double wettable powder or 75% chlorothalonil wettable powder and 35% methaloxin can be used to mix seeds according to 4% of the seed amount. Reasonable crop rotation and timely sowing. Pharmaceutical prevention and control.

Generally, spraying is started when the central disease plant appears in the early stage of the disease, and timely prevention before the onset of the disease is more effective. In the production of Chinese cabbage, spraying should be done before sealing the ridge, generally every 5 7 days, and spraying more than 2 times in a row. Commonly used agents are:

40% ethylphosphine aluminum wettable powder 250 300 times liquid, 25% methalonil wettable powder 800 times liquid, 75% chlorothalonil wettable powder 600 times liquid, 40% synergistic methaloxin 800 times liquid, Pulik water solution 600 times liquid.

1.Choose disease-resistant varieties. There were significant differences in the incidence of disease among species. Chinese cabbage varieties resistant to viral diseases are generally also resistant to downy mildew and can be selected according to local conditions.

2.Seed dressing. Seed dressing with 50% of the seed weight of Fumei double wettable powder or 75% chlorothalonil wettable powder or 35% seed dressing of the seed weight of Apulon (Ruixin mold).

3.Proper crop rotation. It can be rotated with non-cruciferous crops in alternate years, and can be rotated with paddy field crops where conditions permit.

4.Sow at the right time. The appropriate sowing date should be determined according to the stubble, variety and climate.

Early sowing is serious, late sowing is mild, but the heart is insufficient, but in case of high temperature and drought years, Chinese cabbage should be sown late, the disease resistance of hybrids is stronger than that of farmer seeds, and the sowing date can be arranged in front. Chinese cabbage seedlings should start field disease investigation, after the central diseased plant is found, immediately pull out and spray for control, at the end of the rosette to carry out thorough control. In order to facilitate the later prevention and control, 1 empty row can be left for every 6 8 rows of vegetables when the seedlings are set, which is convenient for prevention and control operations.

The agent can be selected with 40% aluminum triethylphosphonate (aluminum ethylphosphon) wettable powder 200 300 times liquid, 70% ethylphosphon aluminum manganese zinc wettable powder 500 times liquid, 70% chlorothalonil wettable powder 600 times liquid or 72% frosturea manganese zinc (Kelu, Keantiling, gram cyanide) 800 1000 times liquid, per 667 square meters with 100 million live spores of Trichoderma wettable powder 267g mixed with water 50L spray, sprayed once every 5 7 days. The occurrence of downy mildew is closely related to viral diseases, so the two diseases should be considered together in order to obtain good control results.