How to treat gray mold on cucumbers in a greenhouse?

Like other fungal diseases, cucumber gray mold readily develops in the greenhouse. Greenhouse conditions are conducive to the mycelium.

The causative agent of the disease is the fungus Botrytis cinerea (gray botrytis). The parasite feeds not only on the tissues of the host plant, but also on dead organic matter in the soil. This gives him the ability to survive during the winter.

To save the crop, it is necessary to immediately take measures to combat the disease at the first sign of its appearance.

Ways of transmission

With the arrival of heat, the overwintered mycelium is activated and begins to multiply. Spores are carried by wind and winged insects over considerable distances.

Another way of transmission of infection is infected seeds that have not undergone the treatment procedure. Most often, low-quality sowing material is purchased from dubious sellers.

Plants with powerful immunity are inaccessible to the fungus; it affects only aging and weakened specimens. Mechanical tissue damage helps to facilitate the introduction of spores.

Having settled on cucumbers, Botrytis begins its destructive activity, releasing toxins and enzymes that dissolve plant tissues. The softened areas serve as a breeding ground for the fungus, it continues to multiply actively and spreads throughout the plant.

When the growing season for cucumbers ends, the pathogen of gray rot moves into the soil, where it is in the form of mycelium and sclerotia until next spring. The life cycle of Botrytis can be repeated many times, and if no measures are taken, the fungus will settle in the greenhouse for a long time, annually damaging the planted crops.

The affected cucumber is deprived of normal nutrition, which causes a decrease in yield. In advanced cases, the plant dies.

The reasons for the development of the disease

The most rapid development of rot occurs at a temperature of + 17-18 ° C and air humidity above 90%. In addition to these parameters, there are other factors that influence the spread of Botrytis. They are mainly associated with improper agricultural practices:

• refusal to comply with the rules of crop rotation;
• sowing untreated seeds;
• inappropriate sanitary conditions in the greenhouse;
• untimely harvesting of plant residues;
• mechanical damage to plants, sunburn;
• a sharp change in temperature;
• improper fertilization;
• use of cold water for irrigation;
• insufficient ventilation;
• thickening of landings.

If the temperature in the greenhouse rises to + 25 ° C, and the humidity falls below 80%, the outbreak of infection dies down. But this does not mean that the fungus has irrevocably disappeared - under favorable conditions, gray rot will return. The disease often develops on weakened plants affected by aphids and powdery mildew.

Manifestation of symptoms

The incubation period of the disease lasts about a week, and only then the symptoms begin to appear:

1. Yellowish-brown spots with uneven edges appear on the stems and leaves.
2. The affected areas gradually grow larger.
3. The middle of the spots begins to get wet, and a border of dried tissue forms around it.
4. The flowers turn brown.
5. In places affected by gray rot, the stem begins to rot.
6. On the tips of the fruit, a gray cannon bloom appears, which spreads quickly.

After seeing these signs, you need to stop watering and fertilizing the cucumbers. In the greenhouse, the vents are opened to improve ventilation.To assess the scale of the lesion, all plantings are examined, after which a method of plant treatment is chosen.

How to treat cucumbers for gray rot?

Those bushes on which the disease is in an advanced stage are best removed from the greenhouse, their treatment is impractical. The remaining wells are poured with a solution of the fungicide "Rovral", prepared according to the instructions. The bed is carefully cleaned of fallen leaves and other debris, the top layer of the earth is removed, fresh soil is added and sprinkled with wood ash on top.

The bushes torn out are burned.

On the remaining plants, it is necessary to clean the decaying areas to healthy tissue, tear off diseased fruits, and then process:

• The wounds can be sprinkled with lime, coal powder or wood ash.
• The stems are smeared with a mixture of wood ash (200 g) and copper sulfate (5 g). Wallpaper glue must be added to the ingredients as a binding element.
• For the same purpose, the drugs "Sumileks" or "Rovral" are used. The composition is pre-mixed in half with chalk and slightly diluted with warm water to obtain a pasty consistency.

How to deal with folk remedies

Folk remedies are effective in combating gray rot only with minor damage. They are also used during the ripening period of the crop, so that you can safely eat cucumbers.

Spraying from the fungus is done 3-4 times at intervals of a week. To make the solution better adhere to the leaves, add laundry soap (40 g per bucket of water).

All proportions are based on 10 liters of water:

• 50 g of soda ash and 80 g of copper sulfate are dissolved in warm water;
• mix 1 liter of natural milk and 10 drops of iodine, then dissolve the mixture in water;
• wood ash in the amount of 300 g is poured with a small amount of water (2-3 liters), boiled for 15-20 minutes, brought to full volume with water and insisted for 3-4 hours;
• diluted in water 2 tsp. brilliant green or 1.5 g of potassium permanganate;
• make an aqueous solution from boric acid (10 g), iodine (30 g) and potassium permanganate (1.5 g).

Processing is carried out in the morning or evening hours on dry leaves, sprinkling on them from both sides. The solution also treats the root zone of plants.

The use of biological products

It is possible to treat cucumbers from gray rot with biological preparations. The advantages of these products in environmental safety are that they do not harm the soil, humans, animals, beneficial insects, and have a short decay period.

Biologicals are not as effective as chemical fungicides, but they can be safely used during the fruiting period. It should be borne in mind that sunlight is destructive for these products, so the treatment should be carried out in cloudy weather.

Against gray rot on cucumbers are used:

• Fitosporin;
• Trichodermin;
• "Glyocladin";
• "Barrier";
• "Gamair".

The order of application and doses are indicated by the manufacturer in the instructions, it must be strictly followed. The processing is carried out 2 or 3 times.

Use of chemical fungicides

Chemicals are used immediately after preparation of the working solution, as they quickly lose their properties.

Fungicides are suitable for the destruction of gray rot:

• "Euparen Multi";
• "Rovral";
• Hom.

It is necessary to apply the drugs 2-3 times, taking breaks for 1.5-2 weeks. During processing, you must use protective clothing, gloves, mask. After working with chemicals, be sure to wash your face and hands, rinse your mouth, wash clothes.

Preventive measures

So that the cucumbers in the greenhouse are not affected by gray rot, it is first of all necessary to observe agricultural practices.

• It is important to choose the right variety - it must be resistant to fungal diseases.
• Seeds of questionable quality must be soaked in a solution of potassium permanganate for 15–20 minutes before sowing.
• The greenhouse in spring and autumn is disinfected with a formalin solution or a 2% Bordeaux mixture.
• The top layer of soil 10-15 cm thick must be replaced annually.
• The bushes are planted in accordance with the scheme and formed during the growth process.
• Water the cucumbers in the morning with warm water.
• Plants need timely feeding and optimal temperature conditions.
• Periodically, preventive treatments are carried out in the greenhouse.

The health of the culture is completely in the hands of the summer resident. It is necessary to think in advance what exactly and where to plant, choose the right variety, take care of the plants in accordance with their requirements. When symptoms of gray rot appear, treatment cannot be postponed until later, it is necessary to start it immediately, then it will be possible to get a harvest of cucumbers without losing the quantity and quality.