Why does powdery mildew appear and why is it dangerous on cucumbers: photo and treatment, preventive measures

Powdery mildew is a fungal disease that affects cucumbers both outdoors and indoors. Spores spread quickly in humid and cool air. In this article, we will talk about the causes of the disease, signs of infection, methods of treatment and prevention.

What is powdery mildew

Powdery mildew, linen, or ash - a disease of a fungal nature... It occurs as a result of plant infection with microscopic ectoparasites. At the beginning of summer, a whitish mycelium multiplies on the leaves and shoots, turning into dew drops. Therefore, the disease got its name.

The pathogen lives in the upper soil layer, on the weeds. Therefore, the lower leaves are infected first. Then the infection gradually spreads upward.

The fungus tolerates winter and wakes up in springwhen the air becomes warm and humid. Spores are carried by wind and raindrops.

Danger to cucumbers

Due to the fungal nature, the disease thrives in humid conditions... Affected cucumber bushes lose their visual appeal and vitality. Plant growth and development are suspended.

Stems and leaves first wither, then dry and die off. Powdery mildew rarely affects the fruit, but the green leaves deprived of nutrition begin to blacken and rot.

Other diseases of cucumbers:

How to deal with cucumber fusarium

Causes and treatment of cucumber anthracnose

Mechanism and development cycles

Powdery mildew (Erysiphe graminis) infects living plant tissue... Distribution occurs by the formation of conidia (immobile spores of asexual reproduction) on the front of the leaves.

Spores are actively formed at a temperature air + 18–20 ° C and high humidity. Viable only for 2-4 days. On the fifth day of infection, new spore colonies appear. During the period of drought, the process of reproduction of conidia and further infection of plants stops.

Life cycle of Erysiphe graminis:

1. Spore germination.
2. Infection.
3. Chains of spondia.
4. Spread of disputes.
5. Formation of male and female reproductive organs.
6. Cleisothecium.
7. Exit spores from ruptured clestothecium.

Symptoms of defeat

Powdery mildew infects cucumbers in early June. It is during this period that the air temperature drops, rains replace the heat.

The disease is indicated by such signs:

• white or yellowish bloom on leaves and stems;
• small brown balls (spores) on the plant;
• dew drops on the leaves;
• dry, twisted leaves;
• traces of rot on the fruit.

What do affected cucumbers look like?

White spots on leaves are small at first... Over time, they grow, the leaves completely turn white, then turn gray and curl upside down.

If the disease is not treated, the plaque thickens and becomes brown, spreads to the whole plant and affects cuttings, stems, ovaries, greens. Cucumbers look like they are covered with mold and begin to rot. This is the last stage of the disease, which does not make sense to treat - unfortunately, the harvest cannot be saved.

How to distinguish from downy mildew

True powdery mildew is often confused with false, which is called peronosporosis. The disease has such distinctive features:

• a large number of small yellow spots appear on the leaves;
• the affected area increases within 5-7 days;
• the leaves turn brown and dry.

Peronosporosis affects plants at any stage of the growing season... It occurs due to high humidity, watering cucumbers with cold water.

Causes of the disease

The main reason is the infection with fungal microorganisms of the vegetative parts of the plant.

Powdery mildew affects cucumbers when:

• sudden changes in temperature;
• lingering rains;
• watering with cold water;
• dense planting of plants;
• non-observance of the rules of agricultural technology (weeding, weeding, loosening the soil);
• lack of sunlight;
• excess nitrogen in the soil;
• lack of potassium and phosphorus.

Often the fungus infects cucumbers in the open field... This is facilitated by drafts, torrential rains, wet soil, temperature fluctuations.

In greenhouses, infection occurs as a result of ventilation, increased humidity. The first symptoms appear on bushes located near the vents or doors.

In greenhouses, cucumbers are infected first.growing near poorly glazed frames or in cool and damp nooks.

Treatment methods

The most effective in the fight against powdery mildew on cucumbers are chemical agents and folk methods based on fermented milk products, ash, manure, soda ash, soda and herbal decoctions.

Folk remedies

Folk remedies used for prophylactic purposes or immediately after the detection of the disease... In a situation where the fungus has covered a large area of ​​cucumber plantings, folk methods are powerless.

The best homemade products are considered:

1. Sour milk, whey, kefir... For 10 liters of water, take 1 liter of a fermented milk product of your choice. The plants are treated as often as required.
2. Soda ash... For 1 liter of water, take a third of a teaspoon of soda and 25 ml of liquid soap. Processing is carried out once a week.
3. Wood ash... A liter can of ash is poured with 5 liters of boiling water and insisted for 24 hours. The prepared liquid is irrigated with bushes once a week.
4. Cow dung... In 10 liters of water, 1 kg of manure is diluted and insisted for 3 days. Then it is passed through a filter and the solution is diluted with water 1:10. Watering is carried out in the evening to prevent sunburn.
5. Horsetail decoction... For 10 liters of water take 1 kg of fresh or 100 g of dried raw materials. Insist one day, then boil for 2 hours over low heat, filter and cool. Water is added to the broth in a ratio of 1: 5. Bushes are processed once a week.
6. Infusion of marigolds... 0.5 buckets of flowers are poured with warm water, insisted for 48 hours, filtered and mixed with 50 g of any soap. The bushes are irrigated twice a week.

Important! Treatment with folk remedies begins during the period of prolonged rains and evening fogs.

Chemicals

The best chemicals to fight powdery mildew on cucumbers:

1. "Bayleton"... The healing effect on the treated bushes lasts up to a month, subject to dry and sunny weather.
2. "Raek"... Begins to act 2 hours after spraying. Protection is enough for a week.
3. "Tiovit Jet"... Protective chemical - up to 7 days.
4. "Topaz"... Plant protection product for 1-2 weeks. Sprayed when the first symptoms of the disease appear and for the purpose of prevention. The first treatment - after the appearance of 8-10 true leaves, the second - at the beginning of flowering, 10 days after the first.
5. Colloidal sulfur solution... For 10 liters of water, take 40 g of the substance. Cucumbers are processed in cloudy weather.
6. Fundazol... 10 g of powder is dissolved in 10 liters of water and at least three treatments of the bushes are carried out at the rate of 1.5 liters per 10 sq. m.
7. "Speed"... Fungicide of systemic action for the treatment and prevention of powdery mildew. 2 ml of the product is diluted in 10 l of water. Consumption per plant - 1 liter. The processing is carried out three times.
8. "HOM"... For 10 liters of water, take 40 g of powder, 100 ml of low-fat milk. Consumption for 10 sq. m - 1 l. Cucumbers are sprayed in the evening, in dry, calm weather.

Read also:

Why is boric acid useful for cucumbers and how to use it

Why do you need processing of cucumbers with brilliant green and how to carry it out

Prevention

Prevention methods will help protect cucumbers from infection with powdery mildew:

1. Cleaning weeds and bushes with roots after harvest.
2. Soil treatment with biological agents ("Alirin-B", "Gamair").
3. Disinfection of the holes with a hot strong solution of potassium permanganate before planting seedlings.
4. Control of nitrogen levels. Its excess stimulates the reproduction of powdery mildew spores.
5. Opt for powdery mildew-resistant cucumber varieties and hybrids.
6. Compliance with the distance between seedlings when transferring to the ground.
7. Preventive treatments with "Fitosporin", "Ordan", "Kuprolux".
8. Compliance with the principle of crop rotation and re-planting of cucumbers in the same place no earlier than two years later.
9. Planting seedlings in sunny areas without drafts.
10. Top dressing of the soil with humus or compost.
11. Thinning cucumber plantings.

Powdery Mildew Resistant Varieties and Hybrids

There are many cucumber varieties and hybrids with immunity against the fungus Erysiphe graminis... We have compiled a list of the best of them.

Competitor

Bee-pollinated high-yielding variety for open and closed ground.

Ant F1

Ultra-early hybrid for greenhouses.

Masha F1

Ultra-early self-pollinated hybrid for open and closed ground.

Goosebump F1

Early ripening hybrid Goosebump for greenhouses, hotbeds, vegetable gardens.

Finger Boy F1

Early maturing parthenocarpic hybrid for closed ground.

Benefit F1

Parthenocarpic hybrid for greenhouses and hotbeds.

Alekseich F1

Early ripening hybrid for greenhouse cultivation.

Swallow F1

Bee-pollinated early ripe hybrid for open ground.

Artek F1

Early maturing bee-pollinated hybrid for open and closed ground.

Conclusion

Powdery mildew on cucumbers is a widespread fungal disease. High air humidity, temperature drops, an excess of moisture and nitrogen in the soil are factors that provoke infection and lightning-fast progression of the disease.

Using more disease-resistant cucumber varieties for growing will minimize the risk of powdery mildew infection. Compliance with crop rotation, watering rules and regular inspection of plants also contribute to prevention.

For treatment, use chemicals and folk remedies with copper, soda, horsetail, marigolds, wood ash.Preventive measures will prevent infection or minimize damage.