Why does white bloom appear on cucumbers in a greenhouse and how to deal with it

Healthy cucumber bushes have a beautiful green color. The appearance of white bloom on various aboveground parts of the bush indicates that the plant is affected by fungal diseases. The fruits of such a plant should not be eaten.

To avoid problems, you must adhere to the rules of crop care. We will tell you more about them later.

Causes of white bloom on greenhouse cucumbers

White bloom on the vegetative parts of cucumbers - a symptom of various fungal diseases... They occur if the plant is weakened, has low immunity. These problems appear when the optimal conditions for growing crops are not observed in the greenhouse:

1. In case of violation of the temperature regime... If the air temperature in the greenhouse drops to + 15 ° С, the development of the bush slows down, at + 10 ° С it stops. When the temperature rises to + 30 ° C, the strength of the plant is aimed at protecting against overheating. When the temperature deviates in any direction, the culture experiences stress, becomes less resistant to various infections and pests.
2. With uneven watering... When the soil dries out, the plant inhibits growth. In waterlogged soil, various rot forms. These factors reduce the immunity of the culture.
3. Failure to comply with the proportions of microelements introduced... An excess of nitrogen makes the culture susceptible to infections.
4. Poor processing of seed... Pathogenic fungi maintain their viability for a long time on untreated seeds, and after planting in the ground, they become active.

Powdery mildew

Real powdery mildew — cucumber disease caused by ectoparasitic fungi of the erythyseaceous, or powdery mildew, fungi... The mycelium in the form of a white bloom resembling flour appears at the beginning on the lower leaves, then passes to all aerial parts of the bush, in neglected cases to the fruits.

After maturation of the mycelium spores, liquid droplets are formed - this determined the name of the disease "powdery mildew". Favorable conditions for the development of the disease - high humidity at an air temperature of + 18 ° C ... + 20 ° C, watering with cold water, poor-quality ventilation, an excess of nitrogen in the soil.

Attention! The bushes located near the windows and doors of the greenhouse are most susceptible to damage by pathogenic fungi.

Causes of the disease:

• non-disinfected seed material;
• the presence of mealy fungi in the untreated soil of the greenhouse;
• the presence of plant remains of last year's bushes.

At the beginning of the disease, small areas of white bloom appear on the leaves.... The affected areas gradually merge into one, completely covering their surface. As a result, the leaves are deformed, dry and fall off. The bush looks lifeless, stops bearing fruit, gradually dies.

White rot

White rot (sclerotinosis) - a disease caused by the fungus Sclerotinia sclerotiorum, affecting all parts of the plant... Its development is caused by high humidity and low air temperature in the greenhouse. The fungus remains in untreated soil and infects plants through various mechanical damage.

Symptom - white spots in the form of cotton wool... The affected areas become watery, rotten, a characteristic rotten smell appears. On the cut of the stem, accumulations of black fungus spores - sclerotia are clearly visible. The disease quickly spreads to the entire plant, causing its death.To stop the infection process at the initial stage, the affected branches are removed.

Peronosporosis

Peronosporosis - downy mildew cucumbers. The appearance of the disease is provoked by excessive moisture in the beds, watering the bushes with cold water, the formation of condensation in the greenhouse, poor ventilation.

Important! The fungus develops only in high humidity conditions. Dry air has a detrimental effect on him.

Yellow or brown spots appear on the inside of the leaves... After that, the outer part of the sheet plate is affected. A pale gray-purple bloom appears on it. Almost immediately, the leaves begin to turn yellow, dry, become brittle. The bush stops bearing fruit and withers. Cucumbers lose their taste. With weak immunity, the bush dies within two weeks.

A light gray, fluffy, mildew-like bloom appears on cucumbers when affected gray mold... Brown spots form on the leaves and branches, the ovary and flowers take on a brown tint. Gray mold causes rotting, the bush gradually dries out.

When the plant is damaged by black rot (ascochitosis) on the stems gray, watery patches appear. Gradually they turn white and expand. The leaves turn brown, the fruits wither, and gradually rot.

Plaque on cucumbers appears with white mosaic... Small light areas are noticeable on the leaves, then they grow and darken, become hard, curl. The bush stops growing, withers.

What to do and how to save the harvest

At the first signs of illness and timely treatment started, help folk methods using means safe for health. In case of more serious injuries, modern chemicals are used to protect plants - pesticides.

Chemicals

With fungal infections in the initial stages, biological products are used:

• «Fitosporin-M»;
• "Gamair";
• "Pseudobacterin-2";
• "Planzir";
• "Baktofit".

To stimulate the defenses of culture, many gardeners use growth stimulants:

• "Immunocytophyte";
• Novosil.

If biological products do not give the expected result, fungicides are used:

• "Acrobat MC";
• "Quadris";
• "Kuproksat";
• "Speed";
• "Topaz";
• "Privent";
• Bayleton;
• Fundazol.

To destroy the pathogenic fungus, it is enough to prepare a 1% solution of these drugs.

Attention! The use of cucumbers for food is possible no earlier than 3 weeks after processing the bushes.

Processing is carried out by spraying the entire bush... It is advisable that the solution falls on the ground around the plants. After processing, the greenhouse room is ventilated. For small lesions, the preparations are diluted with water to a mushy state and applied to an area with a white bloom.

For severe lesions, copper-containing preparations are used:

• "HOM" - 30 g / 10 l of water;
• "Ordan" - 35 ml / 10 l of water;
• "Proton-Extra" - 30-40 ml / 10 l of water;
• "Abiga-Peak" - 50 ml / 10 liters of water.

Traditional methods

In the fight against white bloom on cucumbers many farmers prefer safe traditional methods:

1. Pour baking soda, softened laundry soap with water in a ratio of 1: 1: 20. After the soap is completely dissolved, diseased plants are treated with the finished composition.
2. To 10 liters of water add 1 liter of liquid soap, 6 g of copper sulfate. The composition is sprayed on the bushes.
3. A solution of potassium permanganate - 1 g / 10 l of water - spray the bushes at the first signs of damage.
4. Cucumber beds are powdered with a dry mixture of 20 g of wood ash, 20 g of crushed chalk, 1 g of copper sulfate.
5. Kefir is mixed with water in a ratio of 3:10, 5 g of copper sulfate is added and cucumber beds are sprayed.
6. 50 g of garlic is boiled for 30 sec. in 1 liter of water. The solution is cooled, filtered, mixed with 10 liters of water, and diseased plants are treated.
7. Marigolds are crushed, filled with water (1: 1), insisted for three days. Add 25 g of grated laundry soap to the strained liquid. After dissolving the soap, the cucumbers are sprayed.
8. Wood ash in the amount of 500 g is poured into 3 liters of boiling water, cooled, 7 liters of water are added, the bushes are treated.

Prevention methods

Fungal lesions of cucumbers in the greenhouse can be preventedif you follow the rules of agricultural technology:

1. Replace the topsoil in the greenhouse.
2. Before planting cucumbers, treat the site with a biological product "Gamair", add wood ash.
3. For planting, choose varieties and hybrids that are resistant to crop diseases.
4. Treat the seeds with Fitosporin-M, a pink solution of potassium permanganate.
5. It is better to plant cucumbers if onions, garlic, legumes, cabbage were grown in the greenhouse before them.
6. Maintain the microclimate in the greenhouse, provide air circulation.
7. Thinning plants. In thickened plantings, the roots do not receive a sufficient amount of nutrition, and air access to the plants is difficult.
8. Water the bushes at the root without using cold water.
9. Timely feed with phosphorus, potash fertilizers.
10. Loosen the beds regularly.

Tips from experienced summer residents

Experienced summer residents recommend:

1. To carry out preventive treatments of the culture with "Fitosporin-M", "Ordan".
2. Disinfect working equipment before work.
3. Remove leaves with white bloom immediately, without waiting for the development of the disease.
4. In the spring, before planting crops, fumigate the greenhouse from the inside with sulfur bombs.

Conclusion

White bloom on cucumbers in a greenhouse is a sign of a crop attack by various fungal diseases that can ruin a significant part of the crop. In order for the plants to develop well, to form high-quality fruits, they need careful care.

Knowledge of the symptoms of the disease, the timely detection of fungal infections and the correct measures will help preserve the crop.