Prevention of occurrence and effective methods of treatment of peronosporosis in cucumbers

When growing cucumbers, gardeners are often faced with a wide variety of diseases plants. One of the most dangerous is peronosporosis. If the cucumbers are not treated, the foliage of the affected plant dries up, after which it dies.

Sick cucumber bushes are a depressing sight. The gardener thinks not only about the loss of the crop, but also about the contamination of neighboring plants and related crops. How to help cucumbers with peronosporosis and what to do to prevent diseases in the future - we will tell you in this article.

What is peronosporosis

Peronosporosis cucumbers (downy mildew) is a fungal disease caused by the lower fungi oomycetes.

Cucumbers, like other plants of the pumpkin family, are attacked by Pseudoperonospora cubensis.

Pathogenic spores persist on plant debris and soil. In spring they are carried by wind and raindrops.

Mechanical damage to plants contributes to penetration and infection.

Downy mildew is found everywhere: cucumbers can get sick with it both in the open and in closed ground, that is, in greenhouses and hotbeds.

What is dangerous for cucumbers

The harm of peronosporosis is damage to the leaf apparatus of the vegetable. The tops turn yellow and die off, the processes of photosynthesis are disrupted. Plants can die within a week.

Even if the infected bush blooms and bears fruit, their quality and quantity will be extremely low. Disease losses account for 30-100% of the crop.

Symptoms of defeat

Downy mildew is diagnosed by several characteristic features. Our photos will help to determine the disease.

External signs

On the upper side of the leaf, yellow angular spots appear along the veins. Over time, the lesions become brown. The edges of the leaves are turned upward.

After 1-2 days, a grayish or whitish bloom appears on the back of the leaf plate.

Infected plants are stunted and the stems and root systems weaken. Affected tissues have a faded limp appearance.

Development stages

Downy mildew develops rapidly. The incubation period at a temperature of 18 ° C and a relative humidity of 100% is three days.

The disease passes in several stages, which quickly replace each other:

1. At the initial stage, yellow spots appear.
2. The affected areas become oily. On the back of the leaf spore-bearing organs grow - patches of grayish or white bloom, velvety in appearance.
3. The spots become brown in color and increase in size.
4. The foci of infection merge. The leaf dries up and falls off.
5. The final stage is characterized by large-scale withering away of the leaf apparatus and the death of the plant.

Risk factors

Reducing air temperature to 15-20 º С and rainy weather increase the risk of infection. Planting cucumbers in shaded and poorly ventilated areas contributes to the development of the disease.

Too dense plantings, insufficient insolation, relative humidity above 80% are risk factors for greenhouse vegetables.

Cucumber treatment

Oomycetes are not easy to eradicate. It is unlikely that it will be possible to completely save the crop, but you can help the plants.

Destruction of affected areas

When a small number of leaves are affected, they should be removed without regret and destroyed outside the site. This will help prevent the spread of the infection.

However, such a measure cannot be limited.

Agrotechnical techniques

Agrotechnical control measures include:

1. Regular weeding and removal of crop residues. This technique promotes better ventilation of the plants.
2. Timely and reasonable feeding. Gardeners note that the degree of infection increases with a lack of potassium and phosphorus, as well as with an excess of nitrogen.
3. Airing greenhouses and removing overgrown shoots.

Biological agents

Fungicides of biological origin are recommended for use in the early stages of the disease or for prophylaxis. Let's take a couple of drugs as an example:

1. "Trichodermin". Contains live spores of the fungus Trichoderma sp. When germinating, they release antibiotics and substances that have antifungal effect. The drug is produced in the form of a powder or an aqueous suspension. For spraying plants, a working solution is prepared from 20-4 0 ml of liquid or 20-4 0 g of powder and 5 liters of water. Consumption - 5 liters per 1 hundred square meters. " Trichodermin "is used at a temperature not lower than 18 º С, otherwise beneficial spores are not activated. Safe for bees. May cause allergic reactions on contact.
2. Planriz. Created on the basis of living soil bacteria Pseudomonas fluorescens, which produce natural fungicides. The product is produced in the form of a liquid in bottles of various sizes. To prepare the working liquid, take 10 ml of the mother liquor per 10 liters of water. Root spraying is carried out at the rate of 0.5-1 liters per 1 m². Safe for humans and insects. The shelf life of the drug is limited to three months.

Important! Biologics are incompatible with any pesticide. They should be applied no earlier than two weeks after the last chemistry treatment.

Chemicals

If time is lost and the infection has spread throughout the cucumber garden, only chemical agents will help

For the treatment of peronosporosis, the following drugs are suitable:

1. Previkur Energy. The active ingredients are propamocarb hydrochloride and aluminum fosethyl. The drug with a narrowly targeted action, destroys only oomycetes, which include the causative agents of peronosporosis. 25 ml of the product is diluted in 10 liters of water and watered under the root, avoiding contact with the leaves. The consumption of the working solution is about 10 liters per 1 hundred square meters. A maximum of three treatments are carried out with an interval of 10-14 days.
2. "Cuprolux". A drug based on cymoxanil and copper oxychloride with contact-systemic action. Low hazard for bees and humans. Available in the form of a wettable powder. For spraying, a solution is prepared from 25-30 g of the substance and 10 liters of water. Processing is carried out no more than three times per season with a break of 10-12 days.
3. Copper oxychloride ("HOM") is an inexpensive drug of protective contact action, it is recommended to use it as a prophylactic agent. The frequency of treatments is three times per season with an interval of about two weeks. A liquid for processing plants is prepared from 40 g of substance per 10 liters of water. Spraying is carried out at the rate of 1 liter per 10 m². Possesses moderate danger to humans.

Important! To preserve the effect of chemicals, the underside of the sheet must also be carefully processed.

Traditional methods

Traditional methods are safer, but not as effective as pesticides. Most often they are used as preventive measures or at the very beginning of the disease.

Experienced gardeners are advised to try several recipes:

1. Soda. Dissolve 40 g of baking soda in 5 liters of boiled water, add 15 ml of liquid soap. Spray the bushes and soil with the resulting mixture once a week.
2. Onion peel. Pour 500 g of onion husks into 10 liters of water and boil. Leave to infuse in a dark place for 1-2 days. Strain the infusion and spray the cucumbers several times a month.
3. Potassium permanganate. Spray the plants with a weak solution of potassium permanganate (1-1.5 g per 10 l of water) once a week.
4. Milk serum. Add 30 drops of pharmacy iodine and 30 g of grated laundry soap to 1 liter of milk whey. Spray the bushes as a preventive measure every 10 days.

Features of treatment in a greenhouse and open field

The principles of treatment of peronosporosis are common for indoor and outdoor areas.

The difference is that it is easier to regulate the microclimate in the greenhouse. To reduce humidity, ventilation is often carried out. Bricks or stones are used to maintain the temperature. During the day they warm up, and at night they give off heat. Tanks with water work according to the same principle.

Special care should be taken when using chemicals in the greenhouse. After processing, it is recommended not to enter the room for 24 hours.

Preventive measures

Downy mildew prevention is simple. A number of activities will help protect plants:

1. In the fall, all plant residues must be removed from the beds and burned.
2. Cucumbers are not planted in the same place from year to year.
3. Before planting, the seeds are etched in a 0.1% solution of potassium permanganate for 30 minutes.
4. They follow the rules of agricultural technology: they regularly weed the beds, apply fertilizing in accordance with the needs of the plants.
5. To increase the immunity of vegetables, stimulating drugs are used: potassium humate, "Gumistar", "Baikal EM-1".
6. Water the cucumbers only with warm, settled water.

Resistant varieties and hybrids

Planting plants that are resistant to it will help reduce the risk of downy mildew in the area. There are no varieties and hybrids of cucumbers with full resistance to this disease. However, many of them have sufficient immunity.

So, with an epidemic of downy mildew within 12-18 days from the beginning of fruiting, hybrids such as:

• Artek f1;
• F1 backup;
• Crane f1;
• Swallow f1;
• Octopus f1;
• Eaglet f1;
• Semcross f1;
• Swift f1;
• grade Chizhik, etc.

The following varieties have the maximum possible ability to bear fruit within 21-28 days with a strong spread of the disease:

• Far East 27;
• Moment;
• Phoenix;
• Phoenix plus.

Varieties with complex resistance to pathogens of fungal diseases include:

• Cupid;
• Erofey;
• Cascade;
• Whale;
• Lotus;
• Swag.

Bred and hybrids, not challengesdoubts about their resistance to peronosporosis:

• Brunet f1;
• F1 opening;
• Katyusha f1;
• Beauty f1;
• Strong f1;
• Dandy f1.

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Conclusion

Peronosporosis, or downy mildew, is a fungal infection that can kill plants and the entire crop within a week. Sources of the pathogen are the remains of infected plants, the spores from which are carried by wind and rain drops. Cool (15-20 ° C) and rainy weather contributes to the development of the disease.

Chemical and biological fungicides are used as protection and treatment. The use in a complex of agricultural techniques (removal of infected leaves, weeding, feeding, introduction of immunity stimulants), folk remedies and the cultivation of varieties and hybrids resistant to the disease will help to finally overcome downy mildew.