How to deal with white spots on cucumber leaves, and what are the reasons for white spots on cucumbe

White spots on cucumber leaves are due to powdery mildew. This disease is a common disease during the cultivation of cucumbers, and if it is not transmitted to other cucumbers as soon as possible, it will eventually lead to large-scale diseases. First of all, we can use sulfur powder with accelerant to ignite fumigation, and continue to fumigate for about 12 hours, which can basically eliminate most of the bacteria of powdery mildew.

In the later stage, it can be fumigated again at an interval of about 3 days, which can destroy the germs more thoroughly.

1. Low temperature: too low temperature will cause white spots on cucumber leaves. When the temperature outside suddenly drops a lot, causing the temperature difference to be too large, the cucumber leaves will quickly lose moisture, which will lead to the appearance of white spots.

2. Wind damage: The direction and temperature of the wind blowing are uncomfortable, which sometimes leads to white spots on the leaves. This situation generally occurs in the place of the wind outlet, where the cold wind blows directly on the leaves, causing the leaves to wilt, so that the leaves will gradually fade green and form white spots.

3. Pesticide injury: When the wrong pesticide is applied, or inferior pesticide is used, it will lead to white spots on the leaves of cucumbers. Therefore, when spraying pesticides, it is necessary to choose the right type, and the dosage should be strictly controlled according to the instructions.

Avoid over-medication or low-quality pesticides.

1. Avoid blowing cold air directly.

Cause: If the cold wind blows directly on the warm leaves, it will cause the leaves to lose their green color and form white spots.

Solution: When releasing the wind, the wind should be released against the wind direction, and the tuyere should be gradually increased from small to large, and it should not be rushed. Alternatively, you can hang a piece of plastic film on the inside of the ventilated air to prevent cold air from blowing through.

2. Keep warm in time.

Reason: If the temperature is higher than 0 degrees for a long time, but lower than the temperature of its normal growth, then the leaves are prone to yellow-white green spots, and even lead to death, and there will be slow growth or the phenomenon that the plant does not take root.

Solution: Find out the cause of the low temperature, use insulation measures, control the temperature between 25 and 30 degrees during the day, and not lower than 10 degrees at night, preferably between 10 and 18 degrees.

White spots on cucumber leaves are commonly referred to as powdery mildew. The symptoms of powdery mildew are: small round powdery mold spots grow on the front or back of the lower leaves, gradually expand, thicken, and soon join together.

In the later stage of the disease, the whole leaf is covered with white powder, then turns grayish-white, and finally the leaf is yellowish-brown and dry.

When the environmental conditions deteriorate, white spots appear on the leaves of cucumber plants, and the predisposing factors can be judged according to the environmental conditions and the location and shape of the white spots, so as to take preventive or remedial measures. Cucumber leaves have white spots may be due to cold wind, temperature changes, pesticide disasters, nutrient overload, wrong pesticides and other reasons, these factors can be controlled, find the cause and the right solution can alleviate this problem, usually in the cultivation of cucumbers to maintain more, so that cucumbers can grow better.

Let's take a look at the measures we can take in different situations. If it is caused by downy mildew, in the early stage of the disease, you can spray 600 times of 75% chlorothalonil wettable powder, 600-800 times of 58% Radomir water-dispersible granules, etc. If the temperature is low or the cold wind blows directly, the temperature should be kept within a suitable range, and the suitable temperature for growth is about 25-30 degrees.

In winter, it is necessary to maintain a good temperature to avoid low-temperature frostbite from cucumbers and avoid direct cold winds. Cucumbers are susceptible to white spots or macules if too many pesticides are applied during the management period, because pesticides will corrode the foliage, and sometimes pests crawl over and are not treated in time. Therefore, it is necessary to strengthen management when breeding, and pay attention to controlling the concentration and method of drug when spraying, and strictly follow the instructions to avoid infection and pesticide damage.

If there is excess nutrients, frequent fertilization, excessive nutrients or high concentration of fertilizer will cause fertilizer damage, and it is easy to leave white spots on the leaf surface. At this time, it is recommended to pour water as soon as possible to dilute the fertilizer to avoid aggravation of fertilizer damage. When fertilizing cucumbers, it is necessary to pay attention to controlling the concentration of fertilizer, and thin fertilizer should be applied frequently.

There are generally two cases when cucumber leaves have white spots. First, the cold wind blows to the warm leaves, causing the leaves to lose green, so let the cucumber avoid blowing the cold wind directly, and release it with its back when the wind is released. Second, the ambient temperature is not in line with the growth conditions of cucumbers for a long time, so it is necessary to find out the cause of low temperature and make corresponding protection.

Prevention and control methods: 10% difenoconazole, 25% benzobromidonitrile, 20% flusilazole, prochlorazine, 43% tebuconazole these first-class fungicides, and at the same time with 70% dysenlian, 80% mancozeb, 25% azoxystrobin, 50% pyrazoxystrobin These partial protective agents are used together to treat and prevent diseases.

Causes: The disease is an important disease in cucumber production, mainly harming leaves, mostly occurring in flowering and melon-bearing stages, and the disease is serious in the middle and lower leaves.

At the beginning of the disease, the lesion appears as a water-stained spot, which later turns to light brown, the middle part is lighter, and there is a water-stained pale green halo around it, and the lesion is small, about 1 3 mm in diameter.

In the later stage, the middle part of the lesion is thin paper, pale yellow or grayish-white, brittle and easily broken. When the humidity is high, there will be a few small black spots on the lesions, which are the conidia of the pathogenic bacteria.

<> "Sexual taste: bitter taste, flat.

Medicinal part: the leaf of cucumber of the Cucurbitaceae plant.

Internal: 10-15g, double the fresh; or ground juice drink.

External use: Appropriate amount, pound or grind juice to apply.

Efficacy: Clears dampness and heat, sells deficiency and disinfects swelling.

Indications: main damp heat diarrhea, nameless swelling and poison, wet athlete's foot.

Treatment of children's Wang Feng fever diarrhea, damp heat dysentery: a large handful of cucumber leaves, rub the juice, mix it with boiling water and add white sugar. (Chongqing Herbal Medicine).

The appearance of macula on the leaf surface of cucumber is divided into two types: agricultural control and chemical control.

1. Agricultural prevention and control.

Preference is given to disease-resistant varieties; Reasonable fertilization, drip irrigation and dark irrigation technology under film are used in protected areas; After 9 o'clock, the indoor temperature rises and accelerates, and the vent is closed at this time, so that the indoor temperature in the shed is quickly raised to 34, and the indoor temperature is maintained at 33-34, so as to reduce the indoor air humidity at high temperature and inhibit the occurrence of the disease; After harvesting, the remains of diseased plants are completely removed and taken out of the field for deep burial.

2. Chemical control.

At the early stage of the disease, 25% pyrazoxystrobin emulsifiable concentrate 2500 times, 50% enoylmorpholine wettable powder 1500 times, Pulik water cherry blossom amolator 800 times or 72% frosturea manganese-zinc wettable powder 800 times liquid spray control, once every 5-7 days, 3 times in a row. When applying pesticides, please wear protective clothing, and the application method refers to the amount of agent, application time and safety interval indicated on the product label.

Precautions for cucumber planting

Cucumbers like warmth, not tolerant to cold, the appropriate temperature for growth is 10 32, cucumber high temperature 35 poor photosynthesis, 45 high temperature obstacles, and the temperature is too high will also have an impact on the taste of ordinary varieties of cucumbers, some vegetable friends grow cucumbers bitter, there is a bridge mill may be caused by too high temperature.

When the cucumber is flowering, you can use some potassium dihydrogen phosphate as foliar fertilizer to spray the foliage, as a fertilizer to protect flowers and fruits, and after fruiting, wait for the fruit to grow to the size of a fist for root topdressing, water-soluble fertilizer or compound fertilizer can be used.

1. Avoid blowing cold air.

Cause: If the cold air width blows directly on the warm leaves, it will cause the leaves to lose their green color, which in turn will form white spots.

Solution: When the air is released, it should be in the direction of the wind, and the air outlet should gradually increase from small to large, so that you can not be in a hurry. Alternatively, you can hang a piece of plastic film on the inside of the outdoor air to avoid direct cold wind.

2. Keep warm in time.

Reason: If the temperature is above 0 for a long time, but below its normal growth temperature, then the leaves are prone to yellowish-white green spots, and even cause the plant to die, grow slowly, or not take root.

Solution: Find out the reason for the low temperature, take heat preservation measures, control the temperature between 25-30 degrees during the day, and control the temperature at 10 degrees at night, preferably between 10-18 degrees.