If you want to grow pollution free lettuce, what measures should be taken in terms of diseases?

If lettuce is infected with downy mildew, the main symptoms are reflected on the leaves; In the early stage of downy mildew in lettuce, there will be light yellow irregular spots on the lettuce leaves, and white frost cuticle can be seen on the back. Under suitable environmental conditions, the pathogen will germinate conidia, and the conidia will spread with the help of air flow, irrigation and watering, insects, and agricultural operations, and carry out initial infection or re-infection, and the temperature range suitable for the occurrence of the disease is 15 to 17, and 50% enoylmorpholine wettable powder 1500 times liquid, or 50% frost urea cyanide wettable powder 1500 times liquid, or 72% downy mildew carb water agent 600 times liquid, or 58% nail frost. Manganese-zinc wettable powder 600 times liquid.

<> protect the normal function of the root system, the relative humidity should not be too high for a long time, try to keep the humidity normal, increase air circulation, and help prevent the leaves from being damaged. Proper ventilation makes the water in the leaves dispersible. If the lettuce has rotten leaves, you can first analyze which cause it is probably caused, and then use the medicine rationally according to the situation.

In addition, you can also try to sprinkle crops with 1:2 plant ash and hydrated lime, which can also play a role in sterilization. In the case of prevention, the seeds should be selected first, and it is best to choose the ones with high disease resistance or no pests and diseases.

Then, before sowing, carbendazim and other seeds are sterilized.

Before sowing, combined with land preparation, sufficient basal fertilizer should be applied, generally 2500-3000 kg of well-rotted organic fertilizer per mu, starting from the second year of growth, 50-60 kg of nitrogen fertilizer should be applied every year, which can be applied in batches after returning to green and each mowing combined with tillage and irrigation. In the early stage of whitefly occurrence, you can use the yellow plate to apply engine oil and put it in the field (higher than the plant) to trap and kill the adults, or use 25% chlorpylep wettable powder 1500 2000 times as soon as possible, the most suitable sowing period is 9-10 months, before sowing, you can turn the field deep and use the sun to naturally expose it to kill the harmful bacteria and insect eggs in the soil, and apply 400 kg of rotted farmhouse fertilizer plus 50 kg of calcium and phosphorus fertilizer per mu.

First of all, do not use pesticides, pesticides will have chemical residues. Secondly, it cannot be fertilized, and there will be chemical additives when fertilizing. Finally, of course, you should spend a lot of time in the sun.

In order to effectively prevent and control lettuce black spot disease, timely measures should be taken to prevent and control it. Field management should be strengthened, and the application of organic fertilizer and phosphorus and potassium fertilizer should be increased, which can effectively improve the disease resistance of plants. High-quality disease-free seeds should be selected, and the soil for planting lettuce should be rotated; Remove old and diseased leaves in time and take them away from the planting area to prevent the spread of diseases, and carry out concentrated deep burial or destruction.

Residual branches should be pruned in a timely manner, and water and fertilizer should be well managed, and pesticides should also be sprayed in time to prevent insect pests.

Downy mildew. Lettuce planting in summer and autumn is in the rainy season, so it should be drained in time; In times of drought, avoid long-term flooding; Implement reasonable crop rotation; Improving ventilation conditions, reducing air humidity and soil moisture can reduce downy mildew, and before it occurs, it is controlled by Bordeaux liquid spray. After the occurrence, it is controlled by alternating sprays with 75% chlorothalonil wettable powder 600 times, or 95% downy mildew 500 times, or 64% alum, or 25% methaloxine 800 times, or fast suppression.

First of all, it is necessary not to use pesticides as much as possible, because although pesticides can ensure the quality of lettuce, it will affect his health, and it is impossible for lettuce to be free of residual poison after pesticides.

Once the plant has pests and diseases, you should use plant-specific insecticides, evenly spray on the plant leaves, do not water during the medication period, otherwise it will reduce the efficacy, you can spray several more times to consolidate the effect.

It is necessary to clean up the weeds around the lettuce in time and carry out deep burial treatment to reduce insect roots and pathogens.

Digging drainage ditches, draining water in time, and cleaning ditches in time are also important measures for disease prevention.

When it is found that the leaves have the slightest possibility of disease, the leaves should be cleaned up in time, and at the same time, the leaves should be sprayed with anthrax prevention and control agents.

Weeds in the field and around the field are buried deeply to promote the decomposition of diseased residues and reduce pathogens and insect roots. In addition, open drainage ditches and lower the groundwater level to achieve no stagnant water when the rain stops. After heavy rain, it is an important measure to clean the ditch system in time to prevent moisture retention and reduce the humidity in the field.

The best role of crops is to elongate the plant roots, so that the plant roots maintain a good growth, promote the absorption of soil nutrients by plants, and thus achieve the effect of increasing yield and income The author is slightly familiar with the southern fruit trees, and the following is used as a starting point to talk about the part that needs to be paid attention to in the role of calcium on fruit trees. The effect of calcium on fruit trees Calcium can maintain the stability of cell wall, cell membrane and membrane-bound proteins, and has a positive effect on maintaining peel toughness and preventing fruit cracking.

After the lettuce is sown, as long as the temperature is kept above 0, it can germinate normally, and the temperature should be kept at 20. If the temperature is relatively high, such as higher than 30, it may affect germination, and in severe cases, it may not even be able to germinate. You know, there are subtle differences in temperature requirements for different varieties of lettuce.

Before buying lettuce, you can learn about the peculiarities of this variety.

Lettuce needs a lot of light, so if there is a chronic lack of sunlight in the area, it is not suitable for growing lettuce. If the light conditions are better, the lettuce will grow faster and the growth quality will be better. If there is not enough light, it is likely to slow down the growth of lettuce, and the leaves are not only very thin and tiny.

The roots of the lettuce plant are shallow, so this results in a lack of water absorption as the lettuce grows. Therefore, water management should be taken into account when growing lettuce. When lettuce seedlings are raised, the amount of irrigation can be appropriately increased, so that the soil is always in a relatively moist state, so that lettuce grows better.

When choosing soil, lettuce generally prefers soil that is more porous and has good air permeability, which is not only conducive to the lettuce to absorb water and nutrients, but also conducive to draining stagnant water. In addition, the soil needs to contain nitrogen and phosphorus, which is more conducive to the growth of lettuce. If the soil is well permeable and has a high oxygen content, acidic or neutral is also more conducive to the growth of lettuce.

It is unscientific to blindly pursue the density of planting density, so that even if it is planted, it is basically a small lettuce. One is a matter of nutrition, and the other is a question of space for growth. There are two factors that should be paid attention to in the growth of lettuce:

nutrients and space to grow. If there is not enough space, even if the lettuce has enough nutrients, it will slowly slow down the rate of absorption, resulting in slow growth. Therefore, regardless of whether the soil is fertile or not, everyone should take care to keep enough space during the planting process so that their own management is convenient.

There are many varieties of lettuce. The better varieties are Hangzhou Jian lettuce, Jinan white lettuce and so on. In general, cold-tolerant varieties should be chosen in early spring, and heat-tolerant and sprout-tolerant varieties should be selected in summer and autumn.

After the lettuce is planted slowly, seedling fertilizer should be applied. Each acre of land should be washed with 2 cubic meters of decaying fertilizer and 10 kilograms of urea. Lettuce should not be treated with chlorine-containing fertilizers, otherwise it will affect the taste; When the fleshy stem began to swell, the succulent stem was applied with extraction fertilizer, 10 kg of urea and 15 kg of potassium sulfate per mu; In the case of medium-late maturing varieties, top dressing can be done again after 15-20 days.

It is necessary to make the soil breathable, but also to control the outside temperature, but also to pay attention to the planting density, not to plant too densely, and not too much water.

It is necessary to ensure the permeability of the soil, but also to control the temperature of the outside world, and also pay attention to the density of planting, not to plant too densely, and not to have too much water.

Lettuce planting should pay attention to timely sowing, and the seeds can be directly sown; You can also use the new high-fat film to dress the seeds in advance, gently rake the surface soil with a tooth rake, let the seeds enter the soil, and then spray the new high-fat film 800 times on the surface of the soil to protect the seedlings. Pay attention to the prevention and control of soil compaction.

The demand in the southern market is very high, because the southerners especially like to eat lettuce, lettuce is also more nutritious than slow shooting, and the plant is particularly fond of water, and when planting in the greenhouse, there should be a high temperature, frequent watering, and frequent fertilization.

Lettuce, commonly known as lettuce, is a popular vegetable in Europe and the United States, in recent years, people are more and more in favor of green, pollution-free food, its lettuce has fewer pests and diseases, rich in nutrition, is deeply loved by people, and the demand is increasing year by year. The seedling age is 30 35 days, and the seedling is planted when it has 5 or 6 true leaves. Before planting, 4000 kg of well-rotted high-quality farmhouse fertilizer and 20 kg of compound fertilizer were applied every 667 m2, and 15 20 cm were shallow tillage after general application, and then 1 m wide furrow was made, and the furrow height was 10 15 cm.

In autumn and winter, in order to increase the ground temperature, the ground can be covered with film 1 week in advance, and when the ground temperature is stable above 8, it can be planted. The plant row spacing is 17 20cm, and the planting should be carried out with soil and roots, and the planting depth should not be Dali heart leaves, and the planting water should be watered in time. The temperature of the facility cultivation is controlled at 12 22.

For planting in the high temperature season, the scaffolding should be erected in the morning on the day of planting, covered with shade nets, and transplanted in the evening.

This kind of demand for the old amount can be said to be very high, everyone likes to eat, and then it is particularly cheap, and then there is a very nutritious skin, high-yield technology is best to expand the greenhouse, and then the temperature should not exceed 20 degrees, so as to raise a very delicious dish.

First of all, you can spray some drugs to prevent and control, and secondly, you can use biology to control and protect ladybugs.

The first thing is to choose the right chemical spray, then to use the two drugs to spray together, and then to pay attention to timely insecticide, then to remove weeds, and to ensure the temperature, and be sure to do a good job of soil drainage.

You can place some yellow plates in the field for booby-trapping, you can also spray some pesticides, and you can also add some fertilizers for topdressing in time.

Symptoms of cinerine mold in vegetables. The disease is mostly from the leaves close to the surface, the initial disease part is water-soaked, and the disease part expands rapidly when the humidity is high, and it is brown or light reddish-brown, causing rot, and the disease part has gray mold. The base of the stem is diseased, the diseased part becomes brown and rotten, and there is gray mold control method to select soil for 2 3 years of rotation.

Choose new seedbeds or field seedlings without pathogenic bacteria to cultivate disease-free and strong seedlings. In the morning of cultivated in the protected area, the humidity should be reduced by wind, then the shed should be closed to increase the temperature, and the humidity should be reduced to below 75% in the afternoon. Prevents condensation on leaves at night.

Botrytis occurs under low temperature and high humidity conditions, mainly affecting fruits and also stems and leaves. At first, the cotyledons are yellow, showing a V" shape that develops inward, and then expands to the stem, showing brown lesions, wilting on the upper branches and leaves, and mildew in a humid environment. Basically, it is introduced from the place of decay or wound, and forms a V-shaped lesion on the leaf that expands from the edge to the inside, which can be transmitted by insects and air currents, especially in the case of high temperature and low humidity.

Strengthen cultivation management, the base fertilizer is mainly fully decomposed organic fertilizer, and phosphorus and potassium fertilizers are added to promote fruit and seedlings, and enhance the host's own disease resistance. Promote high-furrow mulching cultivation to reduce soil moisture evaporation and reduce air humidity; Choose reasonable irrigation in the morning on a sunny day, and dark irrigation under the film: first, excessive watering; Second, the weather has been raining for a long time; Third, the density is too large and not ventilated. In short, reduce humidity, ventilate, control watering.

As a precaution, it is recommended to take the above measures; Prevention and control of gray mold special agent + bacterial agent comprehensive spray, or smoke with smoke.

In short, in most cases, doing a good job in garden management can achieve the effect of effectively preventing gray mold, but the beans themselves belong to scaffolding planting, so we should pay more attention to ventilation and light transmission, especially in the spring mildew rainy season, early buckle the shed roasting field to strengthen the protection and field management, planting should not be too dense to prevent the growth of stems and leaves from being too long, pay attention to the temperature and humidity in the shed, protect the plastic film to clean as much as possible to strengthen light fertilization, and find that gray mold is removed in time and buried deeply.

The condition for this disease to occur is that the weather is relatively hot, and the accumulation of moisture causes the roots to rot, so the germs are produced.

The weather environment is not good, the soil lacks nutrients, and the temperature drops at a capricious rate, which can easily cause mildew.

When the temperature reaches about 23 degrees Celsius, germs will develop, and if the humidity reaches 90 or more, it will be easy to get sick.

Downy mildew mainly harms the leaves. It occurs from seedling to maturity cycle, and is more common in the middle and late stages of growth. The lower leaves of the plant are the first to be diseased, and light yellow source spots appear on the leaf surface, which gradually expand into amorphous shapes, or become polygonal due to the restriction of leaf veins, and the spot color becomes yellow-brown, and a sparse frosty fungal layer grows on the back of the spot when wet.

If there are many lesions joined together, the leaves may wilt.

Bamboo shoot brown spot is a disease caused by fungi that mainly damages leaves. Two symptoms are presented. One is a water-stained shape, which gradually expands to an irregular shape, brown to dark gray spots, 2-10 mm in diameter.

The other is dark brown spots with irregular edges, surrounded by a halo in the shape of water stains, dark gray fungi when wet, and in severe cases the spots merge with each other, making the leaves dry up and brown, making sclerotinia sclerotinia a fungal disease, mainly harming the bottom of lettuce. In the later stage of growth, the edge and petiole of senescent leaves in the lower part of the stem on the ground or in contact with the soil are first damaged, and the lesions initially develop into brown water stains, develop into soft tissue type, and the damaged parts are densely covered with cotton wool-like white hyphae, and the sclerotia are produced in the later stage. The sclerotia are white at first, and then gradually turn into black particles in the shape of mouse droppings.

Leaf miners have an inhalation mouth type, with larvae to harm plant leaves, larvae often burrow into the leaf tissue, due to the latent mesophyll tissue leads to irregular white spots on the leaves, resulting in the gradual yellowing of the leaves, resulting in the decomposition of chlorophyll in the leaves, the decline of sugar in the leaves, the leaf yellow of the victim plant falls off, and even dies. Fungal diseases. From the cemetery to the Holy Cycle, it is possible to have an onset.

The onset of the seedling stage is a putrefaction in the shape of a water stain with a gray fungal layer. Most of the disease begins in the leaves close to the ground, which are yellowish-brown in color, and the lesions are moisturized, producing a grayish-brown or grayish-green fungal layer. The onset of the roots is water-stained, the stems rot, the weather is dry, the diseased plants gradually wither and die, and the fungal layer turns white and begins to turn green.

You can use 1000 times of 50% putrid fungus wet powder, 800 times of 40% definomycin suspension, or 800 times of 50% dihomourea wet powder. The above agents should be used in rotation once a week, and spraying three times in a row is sufficient. Mycosis.

The stem is more morbid, causing tissue disease. Rot. There are white cotton-like hyphae on the surface, and there are fecal-like sclerotia of black rats inside, and the upper part of the disease perimeter quickly atrophies and dies.

Low temperatures and humidity, heavy rain, or water accumulation and high density in the fields can all contribute to the disease.