How to prevent and cure 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.