Harmful symptoms and control methods of cucumber powdery mildew

Cucumber powdery mildew is one of the common diseases in cucumber cultivation, which occurs all over the country. Because powdery mildew has produced a certain degree of resistance in recent years, and it can occur all the year round, it is difficult to control it. Therefore, the yield is reduced by about 10% in general years and about 20% in epidemic years. Let's take a look at how to control cucumber powdery mildew.

Symptoms of cucumber powdery mildew

Cucumber powdery mildew suffered the most in leaves, followed by petioles and stems, which generally did not harm the fruit. In the early stage of the disease, small white powder spots appeared on the front or back of the leaves, which gradually expanded into a large area of powder with inconspicuous edges, covered with leaves, as if sprinkled with a layer of white powder. Wipe off the white powder, you can see that the leaves fade green, withered yellow and become brittle. When the disease is serious, the leaves are covered with white powder and turn gray until the whole leaf dies. After powdery mildew infected petiole and tender stem, the symptoms were similar to those on leaves, but the disease spot was smaller and the powdery matter was less. Yellow dots begin to appear on the leaves, and then expand and develop into round or oval spots with a white powdery mildew layer on the surface.

Pathogenic factors of cucumber powdery mildew

The main results are as follows: 1. High planting density, poor ventilation and light transmission, serious disease, too much nitrogen fertilizer, too young growth, low resistance and easy to occur.

2. In the fields with heavy and sour soil, repeated cropping for many years, many diseased bodies in the field, lack of fertility, extensive tillage and overgrown weeds, the plant resistance decreased and the disease was serious.

3. The disease is easy to occur when the fertilizer is not fully mature, the organic fertilizer carries bacteria or the fertilizer is mixed with disease residues of undergraduate crops.

4. Warm climate, dry air, continuous alternation of drought and humidity, lack of light, and long-term dryness after continuous rain.

How to prevent and cure cucumber powdery mildew?

1. Select the land with good ventilation, loose and fertile soil and convenient drainage and irrigation, and properly cooperate with the use of phosphorus and potassium fertilizer to prevent early aging, enhance plant disease resistance, do not water in cloudy days, let out more air in sunny days, and reduce the relative humidity of the greenhouse or greenhouse. Prevent the temperature from being too high to avoid muggy. In the early stage of cucumber powdery mildew or when there is no disease, protective agents are mainly used to prevent the infection of the disease.

2. When the symptoms of powdery mildew appear in the leaves in the field, we should pay attention to the use of quick-acting therapeutic agents and reasonable mixing of appropriate protective agents to prevent the further aggravation and spread of the disease. Experience shows that during the occurrence of powdery mildew, small water can be poured between cucumber rows to increase air humidity, and combined with spraying, the disease can be controlled at one stroke, and auxiliary measures include avoiding excessive application of nitrogen fertilizer, increasing phosphorus and potassium fertilizer, removing diseased tissue after pulling seedlings, and so on.

3. Spraying in time at the initial stage of the disease can be prevented with 1500 times of 25% bacterial suspension or 2000 times of 10% phenylether methyl ether water dispersible granules. Immediately spray 32.5% difenoconazole azoxyrimidine vinegar suspension 1500 times, or 25% pentanol water emulsion 3000 times, or 6% chloropyrimidinol wettable powder 1500 times, or 50% ether bacteria vinegar water dispersible granules 3000 times, or 12.5% enol wettable powder 2000 times, or 33.5% quinolinone suspension 800x. Or 1200 times of 8% flusilazole microemulsion or 30% nonomycete copper microemulsion.

Pictures of cucumber powdery mildew, control of cucumber powdery mildew

Cucumber powdery mildew disease is the main disease in recent years, which reduces the yield of cucumber crops in a large area. Farmers should timely understand the pictures of cucumber powdery mildew and control cucumber powdery mildew.

Among the symptoms of cucumber powdery mildew, leaves suffer the most, followed by petioles and stems, which generally do not harm the fruit. In the early stage of the disease, small white powder spots appeared on the front or back of the leaves, which gradually expanded into a large area of powdery powder with inconspicuous edges, covered with leaves, withered and yellow and became brittle. When the disease is serious, the leaves are covered with white powder and turn gray until the whole leaf dies. After powdery mildew infected petiole and tender stem, the symptoms were similar to those on leaves, but the disease spot was smaller and the powdery matter was less. Yellow dots begin to appear on the leaves, and then expand and develop into round or oval spots with a white powdery mildew layer on the surface. In general, there are more leaves than the upper leaves, and more leaves on the back than on the front. Mildew spots were dispersed alone in the early stage, and then combined into a large mildew spot, which could even cover the whole leaf, seriously affecting photosynthesis, interfering with normal metabolism, causing premature senility and loss of yield.

The pathogenic factors of cucumber powdery mildew can be parasitized on host plants all the year round and become the source of primary infection. The optimum temperature of the pathogen is 20-25 ℃, and the requirement of air relative humidity is not strict. The disease can also occur and spread under the condition of about 25% air relative humidity. When the conditions were suitable in the next year, the conidia germinated and spread to the host leaves with the help of airflow or Rain Water. White mycelial disease spots were formed 5 days later, matured 7 days, and formed conidia to spread and re-infect. Cucumber cultivated in protected field suffered more serious disease because of poor ventilation, high cultivation density, excessive application of nitrogen fertilizer and low-lying fields.

Pictures of cucumber powdery mildew, prevention and control of cucumber powdery mildew: the symptoms of powdery mildew appear in the leaves in the field, we should pay attention to the use of quick-acting therapeutic agents, and pay attention to adding appropriate amount of protective agents to prevent the further aggravation and spread of the disease. Cucumber powdery mildew was sprayed with 27% high fat membrane 80 times solution before the onset of cucumber powdery mildew, and foliar spray was carried out with 2% pyrimidine nucleoside antibiotic 200 times solution, duoyaoqing 600 times solution and 10% high water dispersion 1500 times solution at the initial stage of the disease. You can choose 1000-fold solution of 50% methyl topiramate wettable powder or 75% chlorothalonil or 56% chlorothalonil, which can be sprayed every 5-7 days for therapeutic effect.

The above is the picture of cucumber powdery mildew, cucumber powdery mildew control; farmers should be timely drug control, so that cucumber crops can restore growth.

Pathogenic factors and Control points of Cucumber powdery mildew

Generally speaking, cucumber powdery mildew mainly harms leaves, while stems, leaves and fruits suffer less. Therefore, when treating cucumber powdery mildew, people should be clear about the location of the main harm of powdery mildew, so that they can prescribe the right medicine to the case. today, the editor will introduce to you the causes of cucumber powdery mildew and the main points of prevention and treatment:

Pathogenic factors of cucumber powdery mildew

The main results are as follows: 1. High planting density, poor ventilation and light transmission, serious disease, too much nitrogen fertilizer, too young growth, low resistance and easy to occur.

2. The soil is heavy and sour; there are many diseases and residues in the field due to repeated cropping for many years; in the fields with insufficient fertility, extensive tillage and overgrown weeds, the plant resistance is reduced and the disease is serious.

3. The disease is easy to occur when the fertilizer is not fully mature, the organic fertilizer carries bacteria or the fertilizer is mixed with disease residues of undergraduate crops.

4. warm climate, dry air, continuous alternation of drought and humidity, lack of light, and long-term dryness after continuous rain.

Key points of Control of Cucumber powdery mildew

1. Eradication of pathogens: combined with field management, and Ming Ming to cut off the diseased leaves and old leaves in the lower part of the diseased plant, improve the environmental conditions in the greenhouse, and put an end to the route of transmission.

two。 Select suitable pesticides and do a good job of chemical control. You can choose 50% topzine wettable powder, 20% fenbujin EC 2000ml 3000 times or diazolone wettable powder 3000 times, the general mu solution is 50ml 70kg, sprayed every 7mu every 10 days, pay attention to the rotation of different agents to prevent drug resistance, spray for 3 times in a row, spray evenly on both sides of the leaves when spraying.