How to deal with downy mildew when planting cucumbers? Is there any way to prevent it?

Select disease-resistant varieties, adapt measures to local conditions, and promote the use of disease-resistant varieties in a large area to reduce the incidence rate. Clean the field in time, remove the debris and weeds in the field, remove the diseased leaves in time, and immediately uproot the sporadic diseased plants, remove the pathogen host, cut off all sources of infection, and reduce the pathogen base.

Plant insecticides should be used, evenly sprayed on plant leaves, should not be watered during the medication, otherwise there is no effect, it is best to plant it separately from other crops when planting cucumbers.

First of all, we have to prepare a sprayer, our household sprayer, a bucket of water is estimated to be 15 kilograms, then, add 50 grams of urea to a bucket of water, and then add 100 grams of brown sugar or white sugar to the water, the urea and brown sugar are dissolved, stir evenly, use this amount to basically spray once every other week, spray evenly when spraying, must be sprayed in all aspects, one acre of land needs to be sprayed three barrels, this amount is the most appropriate, this method is mainly to prevent this fungal disease of a role, It can also make cucumbers crisp and sweet when ripe, and reduce the phenomenon of cucumber aging.

Pesticide control: 72 grams of dew wettable powder 600 times liquid, Pulik water agent 800 times liquid, Yibao 1000 times liquid, 25% amicida 1500 times liquid, 8% Redomir wettable powder 500 times liquid The diseased leaves at the adult plant stage first appear water-soaked light green class points, and after expansion, they are yellow-brown polygonal lesions limited by leaf veins, and there is a gray-brown mold layer on the back of the leaf when the air humidity is high. (This mold layer can be distinguished from bacterial keratosis).

Downy mildew mainly occurs on the leaves of cucumbers, when the humidity is high in the air, the back of the leaves will produce a gray-black mold layer, with the development of the disease, the leaves will soon turn yellow and withered, when the disease occurs in the adult stage, the leaves will appear water-soaked patches, showing polygonal shape, cucumber varieties have a large difference in resistance to downy mildew, and more disease-resistant varieties should be selected, such as Jinza No. 1, Jinza No. 2, Jinza No. 3, Jinyan No. 4, Jinyan No. 6, Jinyan No. 7, Xiafeng No. 1, Zaofeng No. 1, Zhongnong No. 5, Bichun, etc. Dense-thorn type cucumbers are usually not resistant to disease, but they are early-ripening.

First of all, the physical method, eliminate the moisture in the shed, reduce the occurrence of the disease, timely release, when the wind, a person in front of the 30cm tuyere, one person in the back, in time to close the skin and close the air outlet, this method can ensure that the temperature drops less, while excluding the moisture in the greenhouse, the main harm of yellowing downy mildew is the cucumber leaves, but in the actual process, stems, peduncles and other parts will also appear certain symptoms, mainly talk about the harmful symptoms of the leaves, in order to facilitate the observation of farmers, cucumbers from the seedling stage, All the way to the adult stage,.

The most suitable temperature for the onset of cucumber downy mildew is 16 24, lower than 10 or higher than 28, more difficult to onset, lower than 5 or higher than 30, basically no disease. The suitable humidity is more than 85%, especially when the leaves have a water film, they are most susceptible to infection. Humidity below 70 leaves are sprayed evenly on the front and back, focusing on the mold layer on the back of the diseased leaves, and spraying the upper healthy leaves to protect them.

In addition, attention should be paid to the selection of downy mildew resistant varieties; Strengthen cultivation management, appropriate sparse planting, and use high furrow cultivation: watering with small water.

First of all, we should choose varieties with strong disease resistance for planting, choose a well-drained place, cover the mulch film to reduce water evaporation when planting, and reduce the humidity of the sail imitation pin, control the temperature and humidity in the appropriate range, and implement the crop rotation system. At the same time, it is also necessary to ensure that the soil is drained and that topdressing is carried out to a certain extent. It is also necessary to control pests and diseases in a timely manner.

You have to choose some high-quality cucumber seedlings to plant, spray some pesticides on the fiber excavation imitation land of cucumber seedlings when planting, and spray some pesticides after planting loose and dressed, and spray pesticides on time according to the speed of cucumber growth.

First of all, it can be controlled by spraying, and secondly, varieties with strong disease resistance can be selected.

Hypertrophy and Fat II Knowledge Classroom: Cucumber downy mildew is harmful, what are the causes of the disease?

Cucumber downy mildew is the most common airflow borne disease in the production of cucumbers in plastic greenhouses, which is characterized by fierce onset, fast spread and severe disease, which can make the whole leaf die within two weeks, reducing the yield by 30% to 50%. In addition to harming cucumbers, winter melons, loofahs, pumpkins and melons can also be harmed, while watermelons are rarely harmed.

Cucumber downy mildew can develop in 5 30, the most suitable temperature for the onset of disease is 15 25, the temperature is higher than 30, and the disease is inhibited. Humidity is the main factor that determines the severity of the disease, under the condition of water droplets, the sporangia can germinate in just an hour, and the invasion can be completed in 2 or 3 hours, while the sporangia can not germinate on dry leaves. After the occurrence of downy mildew, when the humidity is small, the onset is slow, and the lesions are not obvious or small; When the appropriate temperature and relative humidity are above 85%, the disease rises sharply, such as excessive watering, lack of timely ventilation, and long-term condensation on the leaf surface, which can easily lead to the epidemic of diseases.

Prevention and control methods: the prevention and control of cucumber downy mildew should implement the plant protection policy of "prevention first, comprehensive control", select disease-resistant varieties, strengthen cultivation management, supplemented by necessary pesticides for prevention and control.

1) Seed selection. Choose disease-resistant varieties.

2) Grafting. Grafting and root replacement cultivation with pumpkin to enhance disease resistance.

3) Strengthen cultivation management.

apply plantar fertilizer, appropriately increase phosphorus and potassium fertilizer and biological fertilizer; Use non-drip anti-fog film to avoid condensation of the shed film; The ground is fully covered with plastic film, and hay is spread between the rows to reduce soil moisture evaporation and reduce greenhouse humidity; Underground infiltration irrigation or submembrane ditch irrigation is used, small water is watered frequently, and large water flood irrigation is avoided; Reasonable dense planting, after the melon is set, the bottom of the old leaves is removed in time to increase the permeability of the field; The temperature is controlled at 28 35 during the day, and the air is released at night in the early morning and evening, and the night temperature is controlled at 10 14, which reduces the relative humidity in the shed at about 70% and inhibits the infection of germs.

4) High temperature stuffy shed.

When the disease is severe, drop the melon seedlings to 100 cm high in advance, choose a sunny day to release wind and irrigate in the early morning, close the greenhouse at about 10 11 o'clock, so that the greenhouse temperature rises quickly to 42 45, maintain for 2 hours, can kill the pathogenic bacteria on the plant and the soil surface. However, the high temperature is stuffy, and it should not be carried out many times to prevent the plant from weakening.

5) Pharmaceutical prevention and control.

At the beginning of the disease, 250 grams of 45% chlorothalonil tobacco agent or 250 grams of 15% double plague tobacco removal agent were used for every 667 square meters, and the shed was closed overnight after ignition, and ventilation was carried out after 10 a.m. the next day. It is also possible to use 5% chlorothalonil dust agent, 5% Garinon dust agent or 10% vanmycolin dust agent in the early stage of the disease, spray 1 kg per 667 square meters, and spray again every 7 10 days. In addition, you can choose 1500 times of 60% Baitai water dispersant (or 800 times of Pulik water solution, or 3000 times of 80% enoylmorpholine water dispersion granules, or 800 times of 72% gram, or 500 times of 64% alum wettable powder) + 2116600 times + 3000 times of organic silicon + 1% fermented milk + 1% urea mixture spray control, spray once every 7 10 days, 2 3 times in a row.

Spraying should be meticulous and thorough, plants from top to bottom, leaf back, leaf, stem, vine and melon strips, should be sprayed, put can be effective control.

I myself have 10 years of experience in planting early spring cucumbers in cold sheds in Mudanjiang area, and downy mildew will occur every year, especially from mid-May to mid-to-late June. I will talk about the prevention and control methods of downy mildew in protected areas based on my own production management experience. Broad-spectrum fungicides such as carbendazim or chlorothalonil are added to it; Again, try to avoid continuous cropping with melon crops, if you can't open the ground, after the stubble vegetables are left in the garden, the residue is fully cleaned up, and then the high temperature stuffy shed, and then before the cucumber planting, use smoke agent or sulfur to sterilize the shed.

Why downy mildew occurs is induced by those factors. The occurrence of downy mildew is generally caused by high temperature and humidity, so we must avoid watering at high temperatures, followed by using pesticides to prevent and control. The following pesticides are used to prevent and control downy mildew, and ** pesticides, if downy mildew occurs, we must use drugs in time.

Cucumber downy mildew occurs mainly on leaves.

The diseased leaves are light green water-soaked spots at the beginning, limited by the leaf veins after expansion, polygonal, yellow-green to light brown, the later lesions converge into pieces, the whole leaves are dried up, and the gray-black mold layer grows on the lesions on the back of the leaves when wet, and the whole leaves die when they are serious. Cucumber downy mildew is commonly known as black hair, running horse, dry leaves, cucumber planting area is common, the disease mainly harms melon crops, such as loofah, winter melon, bitter gourd, melon, pumpkin, etc. are susceptible to blight, downy mildew will cause plant leaf death, is a common disease of cucumber planting in protected areas.

When the temperature is 28 degrees during the day, the greenhouse vent is opened, the temperature is controlled below 35 degrees, and the most suitable temperature is 32 degrees.

Cucumber downy mildew causes leaf death and slow growth, and can also spread to the roots of cucumber vines, causing cucumber vines to bloom less and fruiting melons to fall off often. Finally until the whole cucumber vine is completely dead.

In fact, this double mold disease can only cause a sharp decrease in the yield of cucumbers, because all these agricultural diseases will affect the final plant growth.

Cucumber downy mildew mainly affects leaves and stems, and tendrils and peduncles are less affected. To improve the resistance of cucumbers, on the one hand, supplement medium and trace elements, reduce temperature, and sprinkle grass and wood ash on the aisle to reduce the humidity in the shed, so as to control the occurrence and development of downy mildew.

The most important thing is that it is very harmful to the leaves, which can easily cause the leaves to turn yellow, wilt, or even fall, and also lead to the rapid death of cucumbers. It can also cause some other molds. Therefore, we must prevent and control it in time, and we must ventilate it in time, control the temperature above 35, and we must remove water and never have humidity.

The main damage site is the leaves, in addition, it can also damage the stem, peduncle, tendrils and other tissues. It can be infected at both the seedling stage and the melon setting stage. After the seedlings are infected, it can be seen that the leaves turn green and yellow unevenly, and gradually evolve into yellow spots, and when the humidity is high, the gray mold layer can be seen on the back of the leaves. According to our previous articles, it can be preliminarily judged that the diseases with mold layer at the lesions are mostly caused by fungal infection.

After further infection, the leaves turn yellow and dry up.

Cucumber downy mildew, also known as dew fungus, commonly known as running horse, black hair, pestilence, etc., is a disease caused by the infection of Cuban pseudodowny mildew and occurs on cucumbers. It mainly harms leaves, stems and inflorescences, and can be affected from seedling stage to adult plant stage, especially cucumber entering the melon harvest stage. Cucumber downy mildew is the most serious epidemic disease in cucumber production in solar greenhouses, which can cause most of the leaves of cucumbers to die within a week or two after the onset of the disease, and the cucumber fields are yellow.

The symptom of cucumber downy mildew is that most of the cucumber leaves die within a week or two after the onset of the disease, and the cucumber field is yellow. The prevention and control methods of cucumber downy mildew include scientific fertilization, fumigation and other methods.

1. Symptoms of cucumber downy mildew.

Cotyledons are infected at the seedling stage, first produce irregular greenish and yellow spots on the reverse side of the cotyledons, and gray-black mold layer on the dorsal lesions when wet, and when the disease gradually develops, the cotyledons quickly turn yellow and dry up.

2. Prevention and control methods of cucumber downy mildew.

Scientific fertilization: apply sufficient basal fertilizer, and do not apply too much nitrogen fertilizer during the growth period to improve the disease resistance of plants. The disease of plants is often related to the imbalance of "carbon and nitrogen ratio" in the body, and the disease is easy when the carbon content is relatively low.

According to this principle, the disease resistance of cucumbers can be improved by increasing the proportion of carbon through foliar fertilizer spraying. Experience has shown that from the time after colonization, urea:glucose (or white sugar):

The ratio of water (:1:100 is prepared into a solution, sprayed once every 5-7 days, sprayed 4 times in a row, and the control effect can reach about 90%.

Fumigation method: use 45% chlorothalonil tobacco agent kilogram hectares evenly distributed in 75 places, use a dark fire to ignite from the inside to the outside, and close the shed. It is advisable to take the medicine in the evening, ventilate the next morning, and smoke once every 7-10 days. It is also effective for powdery mildew and gray mildew.

Cucumber downy mildew**

Cultivation is also directly related to fertilizer and water management and disease occurrence, and low-lying terrain, poor soil texture, insufficient fertilizer, over-dense cultivation, poor ventilation or excessive watering can all lead to aggravation of diseases. After the cucumber enters the vegetative growth stage, the number of watering should not be too much, and the brother should be ventilated and transmitted to the light in time during the day to enhance the disease resistance of the plant. Organic fertilizers should be increased.

Because the organic fertilizer has complete nutrients, stable properties and long fertilizer efficiency, it can continuously meet the needs of cucumber growth at all stages and enhance the ability to resist disease.

At the same time, it is necessary to pay attention to the application of phosphorus and potassium fertilizers, which play an important role in promoting root development and the formation of mechanical tissues, and can improve the disease resistance of cucumbers. Dense planting should be determined according to different varieties, not too dense, high density, poor ventilation, affecting the light effect, but also the main reason for the occurrence of downy mildew.